A077448 Numbers k such that Sum_{d|k} mu(d)*mu(k/d)^2 = +1.

1, 36, 100, 196, 225, 441, 484, 676, 1089, 1156, 1225, 1444, 1521, 2116, 2601, 3025, 3249, 3364, 3844, 4225, 4761, 5476, 5929, 6724, 7225, 7396, 7569, 8281, 8649, 8836, 9025, 11236, 12321, 13225, 13924, 14161, 14884, 15129, 16641, 17689, 17956

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A030229(n)^2.

Sum_{n>=1} 1/a(n) = 21/(2*Pi^2). - Amiram Eldar, Jul 16 2020

Mathematica

Select[Range[135], MoebiusMu[#] == 1 &]^2 (* Amiram Eldar, Jul 16 2020 *)

Prog

(PARI) is(n)=if(!issquare(n, &n), return(0)); my(f=factor(n)[, 2]); if(n>1, #f%2==0 && vecmax(f)==1, n==1) \\ Charles R Greathouse IV, Oct 16 2015

Crossrefs

Cf. A008683, A030229, A077438, A085986 (subsequence).

Sequence in context: A175391 A030627 A177492 * A085986 A027603 A250813

Adjacent sequences: A077445 A077446 A077447 * A077449 A077450 A077451

Keyword

nonn

Author

Benoit Cloitre, Nov 30 2002

Status

approved