a(n) is the smallest nonnegative integer that can be written as a sum of two distinct nonzero triangular numbers in exactly n ways or -1 if no such integer exists.

A342326

a(n) is the smallest nonnegative integer that can be written as a sum of two distinct nonzero triangular numbers in exactly n ways or -1 if no such integer exists.

Terms

    a(0) =0a(1) =4a(2) =16a(3) =81a(4) =471a(5) =2031a(6) =1381a(7) =11781a(8) =6906a(9) =17956a(10) =34531a(11) =123256a(12) =40056a(13) =305256a(14) =863281a(15) =448906a(16) =200281a(17) =1957231a(18) =520731a(19) =10563906a(20) =1001406a(21) =11222656a(22) =7631406a(23) =3454506a(24) =1482081a(25) =75865156a(26) =7172606106a(27) =8852431a(28) =25035156a(29) =334020781

External references