A023149 Numbers k such that prime(k) == 7 (mod k).

1, 2, 4, 6, 18, 36, 78, 191, 6456, 6457, 40080, 40081, 637324, 637326, 637344, 10553425, 10553434, 10553477, 10553502, 10553573, 10553854, 27066988, 27067126, 69709680, 69709736, 69709940, 465769818, 3140421716, 3140421740, 3140421743

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

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

Crossrefs

Cf. A171434, A092049, A023143, A023144, A023145, A023146, A023147, A023148, A023150, A023151, A023152.

Programs

Mathematica

p = 1; Do[ If[ Mod[p = NextPrime[p], n] == 7, Print[n]], {n, 1, 10^9}] (* Robert G. Wilson v, Feb 18 2004 *)

Sage

def A023149(max) :
    terms = []
    p = 2
    for n in range(1, max+1) :
        if (p - 7) % n == 0 : terms.append(n)
        p = next_prime(p)
    return terms
# Eric M. Schmidt, Feb 05 2013

Extensions

More terms from Robert G. Wilson v, Feb 18 2004

a(27)-a(31) from Robert G. Wilson v, Feb 22 2006

First four terms inserted by Eric M. Schmidt, Feb 05 2013