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.

A129556 Numbers k such that the k-th centered pentagonal number A005891(k) = (5k^2 + 5k + 2)/2 is a square.

Table of values

n a(n)
1 0
2 2
3 21
4 95
5 816
6 3626
7 31005
8 137711
9 1177392
10 5229410
11 44709909
12 198579887
13 1697799168
14 7540806314
15 64471658493
16 286352060063
17 2448225223584
18 10873837476098
19 92968086837717
20 412919472031679
21 3530339074609680
22 15680066099727722
23 134059916748330141

List of values

[0, 2, 21, 95, 816, 3626, 31005, 137711, 1177392, 5229410, 44709909, 198579887, 1697799168, 7540806314, 64471658493, 286352060063, 2448225223584, 10873837476098, 92968086837717, 412919472031679, 3530339074609680, 15680066099727722, 134059916748330141]

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

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