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 A365630 #21 Sep 15 2023 18:41:41 %S A365630 1,2,5,10,20,30,52,77,117,162,227,309,414,535,692,873,1100,1369,1661, %T A365630 2030,2438,2925,3450,4108,4759,5570,6440,7457,8491,9798,11020,12593, %U A365630 14125,15995,17820,20074,22182,24833,27379,30422,33351,36996,40346,44445,48336,53048,57494 %N A365630 Number of partitions of n with exactly four part sizes. %H A365630 Alois P. Heinz, <a href="/A365630/b365630.txt">Table of n, a(n) for n = 10..10000</a> %F A365630 G.f.: Sum_{0<i<j<k<l} x^(i+j+k+l)/( (1-x^i)*(1-x^j)*(1-x^k)*(1-x^l) ). %e A365630 a(11) = 2 because we have 5+3+2+1, 4+3+2+1+1. %p A365630 # Using function P from A365676: %p A365630 A365630 := n -> P(n, 4, n): seq(A365630(n), n = 10..56); # _Peter Luschny_, Sep 15 2023 %o A365630 (Python) %o A365630 from sympy.utilities.iterables import partitions %o A365630 def A365630(n): return sum(1 for p in partitions(n) if len(p)==4) # _Chai Wah Wu_, Sep 14 2023 %Y A365630 A diagonal of A060177. %Y A365630 Column k=4 of A116608. %Y A365630 Cf. A000005, A002133, A002134, A365631. %K A365630 nonn %O A365630 10,2 %A A365630 _Seiichi Manyama_, Sep 13 2023