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.

A069062 Numbers k such that k^2-1 and k^2+1 have the same number of positive divisors.

This page as a plain text file.
%I A069062 #17 Jun 04 2022 04:30:00
%S A069062 2,3,12,30,42,60,68,102,108,112,123,128,162,168,198,200,212,213,252,
%T A069062 294,302,312,318,333,336,338,372,387,447,448,450,462,498,502,522,542,
%U A069062 578,592,598,600,606,612,648,672,678,708,717,752,762,795,808,810,812
%N A069062 Numbers k such that k^2-1 and k^2+1 have the same number of positive divisors.
%H A069062 Amiram Eldar, <a href="/A069062/b069062.txt">Table of n, a(n) for n = 1..10000</a>
%t A069062 Select[Range[1000], DivisorSigma[0, #^2 - 1] == DivisorSigma[0, #^2 + 1] &] (* _Amiram Eldar_, Jun 04 2022 *)
%o A069062 (PARI) isok(n) = numdiv(n^2-1) == numdiv(n^2+1); \\ _Michel Marcus_, Nov 24 2013
%Y A069062 Cf. A000005, A002522, A005563, A193432, A347191.
%K A069062 easy,nonn
%O A069062 1,1
%A A069062 _Benoit Cloitre_, Apr 04 2002