A281958 Primes p such that p^2 - 1 is not a totient number (A002202).

2, 173, 317, 509, 709, 773, 787, 947, 1307, 1447, 1579, 1613, 1627, 1867, 2347, 2467, 2693, 3307, 3413, 3547, 3803, 3923, 4007, 4243, 4567, 4597, 4723, 4793, 4813, 4937, 4973, 5227, 5261, 5387, 5483, 5557, 5653, 5717, 5827, 5843, 6277, 6397, 6547, 6653, 6793, 6907

Offset: 1

Author

Altug Alkan, Feb 03 2017

Keywords

• nonn

Comments

Corresponding values of p^2 - 1 are 3, 29928, 100488, 259080, 502680, 597528, 619368, 896808, 1708248, ...

Examples

			Prime number 173 is a term because 173^2 - 1 = 29928 is not a totient number.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A002202, A007617, A084920.

Programs

PARI

is(n) = isprime(n) && !istotient(n^2-1);