A054002 Number of divisors of n such that n and n-1 have the same sum of divisors.

4, 6, 4, 8, 16, 8, 8, 12, 12, 8, 4, 10, 8, 4, 8, 12, 8, 16, 16, 16, 16, 8, 16, 12, 16, 16, 8, 8, 4, 16, 8, 24, 16, 4, 16, 8, 4, 32, 8, 16, 16, 16, 8, 8, 8, 8, 16, 32, 8, 8, 16, 16, 16, 12, 16, 16, 12, 8, 48, 32, 8, 24, 24, 16, 16, 16, 8, 16, 24, 64, 8, 16, 16, 16, 16, 64, 24, 32, 60

Offset: 1

Author

Asher Auel, Jan 12 2000

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10135 (from the b-file at A002961)

Crossrefs

Cf. A000005, A000203, A002961, A053249, A054003.

Programs

Magma

[#Divisors(n):n in [2..3500000]| SumOfDivisors(n) eq SumOfDivisors(n-1)]; // Marius A. Burtea, Sep 07 2019

Formula

a(n) = tau(A002961(n) + 1).

Extensions

More terms from Naohiro Nomoto, Jun 23 2001