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 A089351 #8 Apr 13 2017 16:05:42 %S A089351 1,2,6,14,33,64,127,228,404,672,1100,1724,2661,3974,5849,8402,11911, %T A089351 16556,22751,30772,41198,54436,71283,92316,118609,150950,190753, %U A089351 239090,297783,368236,452782,553240,672532,812980,978211,1171144,1396235 %N A089351 Number of planar partitions of n with trace 4. %C A089351 Also number of partitions of n objects of 2 colors into 4 parts, each part containing at least one black object. %D A089351 G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976 (Ch. XI, exercise 5 and Ch. XII, exercise 5). %F A089351 G.f.: q^4*(q^12+q^10+2*q^9+4*q^8+2*q^7+4*q^6+2*q^5+4*q^4+2*q^3+q^2+1) / ((-1+q^4)^2*(-1+q^3)^2*(-1+q^2)^2*(-1+q)^2). %Y A089351 Column 4 of A089353. Cf. A000219, A005380, A005993 (trace 2), A050531 (trace 3). %K A089351 easy,nonn %O A089351 4,2 %A A089351 _Wouter Meeussen_ and _Vladeta Jovovic_, Dec 26 2003 %E A089351 Edited and extended by _Christian G. Bower_, Jan 08 2004