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 A331387 #15 Apr 17 2021 14:13:45 %S A331387 1,2,4,7,11,16,24,34,47,64,86,113,148,191,245,310,390,486,602,740,907, %T A331387 1104,1338,1613,1937,2315,2758,3272,3871,4562,5362,6283,7344,8558, %U A331387 9952,11542,13356,15419,17766,20425,23440,26846,30696,35032,39917,45406 %N A331387 Number of integer partitions whose sum of primes of parts equals their sum of parts plus n. %C A331387 Primes of parts means the prime counting function applied to the part sizes. Equivalently, a(n) is the number of integer partitions with part sizes in A014689(n) interpreted as a multiset. - _Andrew Howroyd_, Apr 17 2021 %H A331387 Andrew Howroyd, <a href="/A331387/b331387.txt">Table of n, a(n) for n = 0..1000</a> %F A331387 G.f.: 1/Product_{k>=1} 1 - x^(prime(k)-k). - _Andrew Howroyd_, Apr 16 2021 %e A331387 The a(0) = 1 through a(5) = 16 partitions: %e A331387 () (1) (3) (4) (33) (43) %e A331387 (2) (11) (31) (41) (331) %e A331387 (21) (32) (42) (332) %e A331387 (22) (111) (311) (411) %e A331387 (211) (321) (421) %e A331387 (221) (322) (422) %e A331387 (222) (1111) (3111) %e A331387 (2111) (3211) %e A331387 (2211) (3221) %e A331387 (2221) (3222) %e A331387 (2222) (11111) %e A331387 (21111) %e A331387 (22111) %e A331387 (22211) %e A331387 (22221) %e A331387 (22222) %e A331387 For example, the partition (3,2,2,1) is counted under n = 5 because it has sum of primes 5+3+3+2 = 13 and its sum of parts plus n is also 3+2+2+1+5 = 13. %t A331387 Table[Sum[Length[Select[IntegerPartitions[k],Total[Prime/@#]==k+n&]],{k,0,2*n}],{n,0,10}] %o A331387 (PARI) seq(n)={my(m=1); while(prime(m)-m<=n, m++); Vec(1/prod(k=1, m, 1 - x^(prime(k)-k) + O(x*x^n)))} \\ _Andrew Howroyd_, Apr 16 2021 %Y A331387 Column sums of A331385. %Y A331387 Partitions into primes are A000607. %Y A331387 Partitions whose sum of primes is divisible by their sum are A331379. %Y A331387 Partitions whose product divides their sum of primes are A331381. %Y A331387 Partitions whose product equals their sum of primes are A331383. %Y A331387 Cf. A000040, A001414, A014689, A056239, A330950, A330953, A330954, A331378, A331415, A331416, A331418. %K A331387 nonn %O A331387 0,2 %A A331387 _Gus Wiseman_, Jan 17 2020 %E A331387 Terms a(31) and beyond from _Andrew Howroyd_, Apr 16 2021