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 A064573 #11 Oct 12 2018 00:51:54 %S A064573 0,1,2,4,5,8,9,13,15,20,21,29,30,37,40,50,51,64,65,80,84,99,100,123, %T A064573 125,146,151,178,179,212,213,249,255,292,295,348,349,396,404,466,467, %U A064573 535,536,611,622,697,698,801,803,900,910,1025,1026,1152,1156,1298,1311 %N A064573 Number of partitions of n into parts which are all powers of the same prime. %C A064573 The exponents cannot all be zero. %H A064573 Andrew Howroyd, <a href="/A064573/b064573.txt">Table of n, a(n) for n = 1..1000</a> %F A064573 G.f.: Sum_{k>=1} 1/(Product_{r>=0} 1-x^(prime(k)^r)) - 1/(1-x). - _Andrew Howroyd_, Dec 29 2017 %e A064573 a(5)=5: 5^1, 3^1+2*3^0, 2^2+1, 2*2^1+1, 2^1+3*2^0 %e A064573 From _Gus Wiseman_, Oct 10 2018: (Start) %e A064573 The a(2) = 1 through a(9) = 15 integer partitions: %e A064573 (2) (3) (4) (5) (33) (7) (8) (9) %e A064573 (21) (22) (41) (42) (331) (44) (81) %e A064573 (31) (221) (51) (421) (71) (333) %e A064573 (211) (311) (222) (511) (422) (441) %e A064573 (2111) (411) (2221) (2222) (711) %e A064573 (2211) (4111) (3311) (4221) %e A064573 (3111) (22111) (4211) (22221) %e A064573 (21111) (31111) (5111) (33111) %e A064573 (211111) (22211) (42111) %e A064573 (41111) (51111) %e A064573 (221111) (222111) %e A064573 (311111) (411111) %e A064573 (2111111) (2211111) %e A064573 (3111111) %e A064573 (21111111) %e A064573 (End) %t A064573 Table[Length[Select[IntegerPartitions[n],PrimePowerQ[Times@@#]&]],{n,30}] (* _Gus Wiseman_, Oct 10 2018 *) %o A064573 (PARI) first(n)={Vec(sum(k=2, n, if(isprime(k), 1/prod(r=0, logint(n,k), 1-x^(k^r) + O(x*x^n)) - 1/(1-x), 0)), -n)} \\ _Andrew Howroyd_, Dec 29 2017 %Y A064573 Cf. A028422, A064572, A064574, A064575, A064576, A064577, A319071, A320322, A320325. %K A064573 easy,nonn %O A064573 1,3 %A A064573 _Marc LeBrun_, Sep 20 2001 %E A064573 Name clarified by _Andrew Howroyd_, Dec 29 2017