A357461 Odd numbers whose number of deficient divisors is equal to their number of nondeficient divisors.

3010132125, 4502334375, 5065535475, 6456074625, 8813660625, 9881746875, 15395254875, 15452011575, 16874983125, 18699305625, 19814169375, 19909992375, 21380506875, 25366375125, 26643400875, 26746594875, 28943578125, 31562182575, 33074966925, 34315506225, 35300640375

Offset: 1

Author

Amiram Eldar, Sep 29 2022

Keywords

• nonn

Comments

The odd terms of A357460.

If there are no odd perfect numbers, then this sequence is also the subsequence of the odd terms of A335543.

The first 100 terms are all divisible by 4725 = 3^3 * 5^2 * 7.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..100

Crossrefs

Subsequence of A005101, A005231 and A357460.

Cf. A335543.

Programs

PARI

is(n) = n%2 && sumdiv(n, d, if(sigma(d, -1) < 2, 1, -1)) == 0;