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.

A324526 Numbers m such that gcd(sigma(m), pod(m)) = tau(m) where tau(k) = the number of divisors of k (A000005), sigma(k) = the sum of the divisors of k (A000203) and pod(n) = the product of divisors of k (A007955).

Original entry on oeis.org

1, 14, 22, 38, 46, 56, 62, 86, 94, 110, 118, 134, 142, 150, 158, 166, 184, 206, 214, 254, 262, 278, 286, 302, 326, 334, 342, 358, 374, 382, 398, 422, 430, 446, 454, 478, 486, 494, 502, 504, 526, 542, 566, 568, 612, 614, 622, 638, 646, 662, 670, 694, 718, 726
Offset: 1

Views

Author

Jaroslav Krizek, Mar 05 2019

Keywords

Comments

Numbers n such that A306682(n) = A000005(n).

Examples

			14 is a term because gcd(sigma(14), pod(14)) = gcd(24, 196) = 4 = tau(14).
		

Crossrefs

Programs

  • Magma
    [n: n in [1..10^5] | GCD(SumOfDivisors(n), &*[d: d in Divisors(n)]) eq NumberOfDivisors(n)]
    
  • PARI
    isok(n) = my(d=divisors(n)); gcd(vecsum(d), vecprod(d)) == #d; \\ Michel Marcus, Mar 05 2019