A182142 Abundance d = sigma(N) - 2*N = A033880(N) of numbers N = A153501(n), i.e., N has d > 0 as divisor.

4, 3, 2, 12, 10, 8, 4, 2, 120, 7, 56, 78, 8, 2, 2, 672, 32, 16, 4, 2, 532, 152, 136, 8, 68, 31, 992, 128, 8, 64, 32, 16, 4, 8, 128, 32, 8, 2, 43648, 2528, 32, 4, 2, 523776, 32, 2272, 32, 32, 127, 16256, 32, 32, 4, 536, 8, 32, 8, 52, 16, 32, 41044, 64

Offset: 1

Author

M. F. Hasler, Apr 14 2012

Keywords

• nonn

Comments

It is conjectured that only powers of 2 can occur more than once.

Thanks to Amiram Eldar, reference to A181595 in the definition has been corrected to A153501 (which does include triperfect numbers, as required here, in contrast to A181595 where these are excluded). - M. F. Hasler, Sep 11 2019

Links

• M. F. Hasler, Table of n, a(n) for n = 1..200, Sep 11 2019

Crossrefs

Cf. A033880, A153501, A181595.

Programs

PARI

f182142(n)={my(d=sigma(n)-2*n); d>0 && !(n%d) && return(d)} /* Note: This is A033880(n)*is_A153501(n), neither A182142 nor is_A182142. */
for(n=1,1e6,(t=f182142(n))&&print1(t","))

Formula

Equals A033880 o A153501.