Solutions by Bruce Gray for https://theweeklychallenge.org/blog/perl-weekly-challenge-149/
Languages: Raku, Perl, C

Task 1: Generate https://oeis.org/A028840
Task 2: Generate https://oeis.org/A287298

Sample runs:
$ perl perl/ch-1.pl 30
$ raku raku/ch-1.raku 30
$ gcc -Wall c/ch-1.c && ./a.out 30
    All have the output:
    0, 1, 2, 3, 5, 8, 10, 11, 12, 14, 17, 20, 21, 23, 26, 30, 32, 35, 41, 44, 49, 50, 53, 58, 62, 67, 71, 76, 80, 85
    
$ perl perl/ch-2.pl 2-12 14-16 18-19
     2           1                     1         1                 1
     3           1                     1         1                 1
     4          15                   225        33              3201
     5          24                   576        44              4301
     6         195                 38025       523            452013
     7         867                751689      2346           6250341
     8        3213              10323369      6215          47302651
     9       18858             355624164     27773         823146570
    10       99066            9814072356     99066        9814072356
    11      528905          279740499025    331413       A8701245369
    12     2950717         8706730814089    BA3711      B8750A649321
    14   105011842     11027486960232964   DD3789C    DC71B30685A924
    15   659854601    435408094460869201  3CDE271B   EDAC93B24658701
    16  4285181505  18362780530794065025  FF6AAE41  FED5B39A42706C81
    18  198009443151  3.92077395769691e+22  HH7CF68B9  HGF80ADC537126GBH2
    19  1404390324525  1.97231218361943e+24  46D29B1F53  IHGFD3408C68ID1IBG7
(21m38s runtime)
$ raku raku/ch-2.raku 2-12 14-16 18-19
     2           1                     1         1                 1
     3           1                     1         1                 1
     4          15                   225        33              3201
     5          24                   576        44              4301
     6         195                 38025       523            452013
     7         867                751689      2346           6250341
     8        3213              10323369      6215          47302651
     9       18858             355624164     27773         823146570
    10       99066            9814072356     99066        9814072356
    11      528905          279740499025    331413       A8701245369
    12     2950717         8706730814089    BA3711      B8750A649321
    14   105011842     11027486960232964   DD3789C    DC71B30685A924
    15   659854601    435408094460869201  3CDE271B   EDAC93B24658701
    16  4285181505  18362780530794065025  FF6AAE41  FED5B39A42706C81
    18  198009443151  39207739576969100808801  HH7CF68B9  HGF80ADC53712EB649
    19  1404390324525  1972312183619434816475625  46D29B1F53  IHGFD3408C6E715A2B9
(4m51s runtime)
$ gcc -Wall -lgmp c/ch-2.c && ./a.out 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16    18 19 20   22 23 24 
f(2)='1'
f(3)='1'
f(4)='3201'
f(5)='4301'
f(6)='452013'
f(7)='6250341'
f(8)='47302651'
f(9)='823146570'
f(10)='9814072356'
f(11)='a8701245369'
f(12)='b8750a649321'
f(13)='cba504216873'
f(14)='dc71b30685a924'
f(15)='edac93b24658701'
f(16)='fed5b39a42706c81'
f(18)='hgf80adc53712eb649'
f(19)='ihgfd3408c6e715a2b9'
f(20)='jihg03dac457bfe96281'
f(22)='lkjig5d14b9032fhac867e'
f(23)='mlkjefg5ic1d9h8042ab376'
f(24)='nmlkjbgc6a0d579482i3efh1'
(13m20s runtime)