Number of arrays of 6 integers in -n..n with sum zero.

Terms

a(0) =1a(1) =141a(2) =1751a(3) =9331a(4) =32661a(5) =88913a(6) =204763a(7) =418503a(8) =782153a(9) =1363573a(10) =2248575a(11) =3543035a(12) =5375005a(13) =7896825a(14) =11287235a(15) =15753487a(16) =21533457a(17) =28897757a(18) =38151847a(19) =49638147a(20) =63738149a(21) =80874529a(22) =101513259a(23) =126165719a(24) =155390809a(25) =189797061a(26) =230044751