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.

A287472 Triangular numbers k such that phi(k) is also a triangular number, where phi(k) is the Euler totient function (A000010).

Table of values

n a(n)
1 1
2 231
3 1035
4 6786
5 190036
6 193131
7 766941
8 1237951
9 1348903
10 3069003
11 3396921
12 8034036
13 9152781
14 11875501
15 15694003
16 28001386
17 29587278
18 35149920
19 61643856
20 63196903
21 130758706
22 178161126
23 198214005
24 227751153
25 268111746
26 339210081
27 402102261
28 654224878

List of values

[1, 231, 1035, 6786, 190036, 193131, 766941, 1237951, 1348903, 3069003, 3396921, 8034036, 9152781, 11875501, 15694003, 28001386, 29587278, 35149920, 61643856, 63196903, 130758706, 178161126, 198214005, 227751153, 268111746, 339210081, 402102261, 654224878]

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

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