cp's OEIS Frontend

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.

A232619 Numbers k such that sigma(k) and sigma(2*k) are triangular numbers.

Table of values

n a(n)
1 1
2 3199808
3 36210072
4 48138616
5 106449517
6 109040509
7 109903789
8 110003837
9 204102760401
10 3050610977780
11 3655577208308
12 3660654715316
13 3660725004788
14 5607890017600
15 6123048180800
16 7412048520512
17 7471435008064
18 53218856249194
19 53221469311786
20 71505497845764
21 103285924642372
22 176553289677888
23 176596975245888
24 176600346573888

List of values

[1, 3199808, 36210072, 48138616, 106449517, 109040509, 109903789, 110003837, 204102760401, 3050610977780, 3655577208308, 3660654715316, 3660725004788, 5607890017600, 6123048180800, 7412048520512, 7471435008064, 53218856249194, 53221469311786, 71505497845764, 103285924642372, 176553289677888, 176596975245888, 176600346573888]

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

Content is available under The OEIS End-User License Agreement.