A069148 Numbers k such that k*k!/A062758(k) is not an integer where A062758(k) is the product of squares of divisors of k.

4, 6, 8, 10, 14, 16, 18, 20, 22, 26, 28, 34, 38, 42, 44, 46, 52, 58, 62, 66, 68, 74, 76, 78, 82, 86, 92, 94, 102, 106, 114, 116, 118, 122, 124, 134, 138, 142, 146, 148, 158, 164, 166, 172, 174, 178, 186, 188, 194, 202, 206, 212, 214, 218, 222, 226, 236, 244, 246

Offset

1,1

Links

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

Mathematica

Rest[Position[Table[(n*n!)/(Times@@Divisors[n])^2, {n, 250}], _?(!IntegerQ[ #]&)]//Flatten] (* Harvey P. Dale, Apr 24 2019 *)
Select[Range[250], !Divisible[#!, #^(DivisorSigma[0, #] - 1)] &] (* Amiram Eldar, Jul 07 2022 *)

Prog

(PARI) for(n=1, 320, if((n*(n!))%(n^numdiv(n))>0, print1(n, ", ")))

Crossrefs

Complement of A069149.

Cf. A001563 (n*n!), A062758.

Sequence in context: A316262 A075124 A067315 * A328144 A327888 A103800

Adjacent sequences: A069145 A069146 A069147 * A069149 A069150 A069151

Keyword

easy,nonn

Author

Benoit Cloitre, Apr 08 2002

Status

approved