A058501 Primes p such that largest odd factor of p-1 is not a prime (i.e., is composite or 1).

2, 3, 5, 17, 19, 31, 37, 43, 61, 67, 71, 73, 79, 101, 103, 109, 127, 131, 139, 151, 157, 163, 181, 191, 197, 199, 211, 223, 229, 239, 241, 251, 257, 271, 277, 281, 283, 307, 311, 313, 331, 337, 349, 367, 373, 379, 397, 401, 409, 419, 421, 431, 433, 439, 443

Offset

1,1

Links

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

Formula

Nonprimes in A057023.

Example

127 is here because 127 - 1 = 126 = 2*63 and 63 is not a prime. 2 is here because 2 - 1 = 1 = 1*2^0 and 1 is not a prime.

Mathematica

lofQ[n_]:=Module[{c=Select[Divisors[n-1], OddQ][[-1]]}, !PrimeQ[c]]; Select[ Prime[ Range[100]], lofQ] (* Harvey P. Dale, Jul 24 2021 *)

Crossrefs

Cf. A057023, A006093.

Sequence in context: A129673 A215372 A290043 * A215356 A249410 A390918

Adjacent sequences: A058498 A058499 A058500 * A058502 A058503 A058504

Keyword

nonn

Author

Labos Elemer, Dec 20 2000

Status

approved