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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.

A203691 Vandermonde sequence using x^2 + xy + y^2 applied to the first n triangular numbers: 1,3,6,10,...,n(n+1)/2.

Table of values

n a(n)
1 1
2 13
3 35217
4 106499166228
5 1193900625351298928700
6 125977443935710401573828500229372900
7 267622663746762354024098339277838006317831656007585600

List of values

[1, 13, 35217, 106499166228, 1193900625351298928700, 125977443935710401573828500229372900, 267622663746762354024098339277838006317831656007585600]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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