Number of 5-element subsets of [n] whose sum is a triangular number.

Terms

a(0) =1a(1) =1a(2) =4a(3) =9a(4) =18a(5) =35a(6) =61a(7) =100a(8) =156a(9) =235a(10) =342a(11) =482a(12) =664a(13) =895a(14) =1185a(15) =1542a(16) =1977a(17) =2505a(18) =3134a(19) =3879a(20) =4757a(21) =5782a(22) =6968a(23) =8337a(24) =9909a(25) =11699a(26) =13732a(27) =16030a(28) =18615a(29) =21514