A325439 - OEIS

A325439

Indices of primes of the form k^2 + 1 ending in 7.

3, 4, 6, 7, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 23, 24, 26, 27, 29, 32, 34, 35, 36, 38, 40, 43, 45, 48, 50, 51, 52, 55, 56, 57, 59, 62, 64, 65, 66, 68, 70, 71, 72, 73, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 87, 89, 90, 91, 95, 97, 98, 99, 101, 103, 107

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OFFSET

1,1

COMMENTS

This sequence is presumably infinite. See 1st comment of A002496.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

A002496(a(n)) mod 10 = 7.

MAPLE

P:=[seq(k mod 10, k=select(isprime, [2, seq(4*i^2+1, i=1..10000)]))]:

seq(`if`(P[i] mod 10 = 7, i, NULL), i=1..nops(P));