a(n) is the sum of n consecutive triangular numbers immediately preceding a triangular number T(k), which is also equal to the sum of n-1 consecutive triangular numbers immediately following T(k).

A392441

a(n) is the sum of n consecutive triangular numbers immediately preceding a triangular number T(k), which is also equal to the sum of n-1 consecutive triangular numbers immediately following T(k).

Terms

    a(0) =0a(1) =36a(2) =361a(3) =1684a(4) =5410a(5) =13880a(6) =30611a(7) =60536a(8) =110244a(9) =188220a(10) =305085a(11) =473836a(12) =710086a(13) =1032304a(14) =1462055a(15) =2024240a(16) =2747336a(17) =3663636a(18) =4809489a(19) =6225540a(20) =7956970a(21) =10053736a(22) =12570811a(23) =15568424a(24) =19112300a(25) =23273900a(26) =28130661a(27) =33766236a(28) =40270734a(29) =47740960

External references