A064937 Nonprimes k such that gcd(k, prime(k)^2 - 1) is 1.

1, 25, 49, 55, 77, 119, 133, 143, 155, 161, 169, 185, 187, 203, 209, 217, 221, 235, 247, 275, 287, 289, 295, 301, 325, 329, 361, 365, 371, 377, 391, 403, 407, 415, 425, 427, 437, 451, 455, 469, 473, 485, 493, 497, 505, 511, 517, 527, 529, 539, 553, 559, 583

Offset: 1

Author

Robert G. Wilson v, Oct 26 2001

Keywords

• easy
• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A064830.

Programs

Mathematica

Select[ Range[600], !PrimeQ[ # ] && GCD[ #, Prime[ # ]^2 - 1] == 1 & ]

PARI

{ n=0; for (m=1, 10^9, if (isprime(m), next); if (gcd(m, prime(m)^2 - 1) == 1, write("b064937.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Sep 30 2009