A159973 Non-refactorable numbers: number of divisors of n does not divide n.

3, 4, 5, 6, 7, 10, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 85

Offset

1,1

Links

Table of n, a(n) for n=1..71.

Mathematica

Select[Range[100], Mod[#, DivisorSigma[0, #]]!=0&] (* Harvey P. Dale, Aug 31 2023 *)

Prog

(Magma) [ n: n in [1..85] | n mod #Divisors(n) ne 0 ];

Crossrefs

Complement of A033950.

Sequence in context: A092860 A351392 A112874 * A359772 A158008 A106155

Adjacent sequences: A159970 A159971 A159972 * A159974 A159975 A159976

Keyword

nonn

Author

Jaroslav Krizek, Apr 28 2009

Extensions

Edited and extended by Klaus Brockhaus, Apr 29 2009

Status

approved