This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A328163 #7 Oct 09 2019 10:02:41 %S A328163 0,0,1,1,2,1,4,2,5,5,9,5,15,9,19,16,28,16,44,21,55,38,73,34,109,46, %T A328163 130,73,170,66,251,78,287,137,364,119,522,135,590,236,759,190,1042, %U A328163 219,1175,425,1460,306,2006,347,2277,671,2780,471,3734,584,4197,1087 %N A328163 Number of integer partitions of n whose unsigned differences have a different GCD than the GCD of their parts all minus 1. %C A328163 Zeros are ignored when computing GCD, and the empty set has GCD 0. %e A328163 The a(2) = 1 through a(12) = 15 partitions (A = 10, B = 11, C = 12): %e A328163 (2) (3) (4) (5) (6) (7) (8) (9) (A) (B) (C) %e A328163 (22) (33) (52) (44) (63) (55) (83) (66) %e A328163 (42) (62) (72) (64) (92) (84) %e A328163 (222) (422) (333) (73) (722) (93) %e A328163 (2222) (522) (82) (5222) (A2) %e A328163 (442) (444) %e A328163 (622) (552) %e A328163 (4222) (633) %e A328163 (22222) (642) %e A328163 (822) %e A328163 (3333) %e A328163 (4422) %e A328163 (6222) %e A328163 (42222) %e A328163 (222222) %t A328163 Table[Length[Select[IntegerPartitions[n],GCD@@Differences[#]!=GCD@@(#-1)&]],{n,0,30}] %Y A328163 The complement to these partitions is counted by A328164. %Y A328163 The GCD of the divisors of n all minus 1 is A258409(n). %Y A328163 The GCD of the prime indices of n all minus 1 is A328167(n). %Y A328163 Partitions whose parts minus 1 are relatively prime are A328170. %Y A328163 Cf. A000837, A018783, A175342, A279945, A289508, A328168, A328169. %K A328163 nonn %O A328163 0,5 %A A328163 _Gus Wiseman_, Oct 07 2019