A261989 Numbers such that A017666(n) = A017668(n).

1, 65, 175, 20737, 32045, 41474, 64090, 128180, 207370, 207553, 352529, 415106, 705058, 1264957, 1762645, 1824877, 2075530, 2529914, 3525290, 3628975, 3649754, 7050580, 7590250, 10223341, 12649570, 17626450, 20446682, 21504269, 23723401, 36321775, 40893364, 43008538, 45621925

Offset

1,2

Links

Michel Marcus, Table of n, a(n) for n = 1..61

Example

sigma(65,-1) = 84/65 and sigma(65,-2) = 68/65, both having the same denominator, so 65 is a term.
sigma(32045, -1) = 9072/6409 and sigma(32045, -2) = 6736/6409, both having the same denominator, so 32045 is a term.

Prog

(PARI) isok(n) = denominator(sigma(n, -1))==denominator(sigma(n, -2));

Crossrefs

Cf. denominator of sum of powers of divisors of n: A017666 (-1st powers), A017668 (-2nd powers).

Sequence in context: A044778 A054902 A255244 * A051968 A242318 A200867

Adjacent sequences: A261986 A261987 A261988 * A261990 A261991 A261992

Keyword

nonn

Author

Michel Marcus, Sep 19 2015

Status

approved