A301944 Number of primes of the form b^2 + 1 for b <= 10^n that end in 7.

2, 13, 68, 560, 4418, 35953, 304340, 2636531, 23265760, 208241341, 1884492541

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Formula

a(n) + A301943(n) + 2 = A206709(n).

Example

17, 37, 197, 257, 577, 677, 1297, 2917, 3137, 4357, 5477, 7057 and 8837 are primes; so a(2) = 13.

Crossrefs

Cf. A002496, A206709, A301943.

Sequence in context: A097977 A373199 A136780 * A128743 A218184 A264735

Adjacent sequences: A301941 A301942 A301943 * A301945 A301946 A301947

Keyword

nonn,base,more

Author

Seiichi Manyama, Mar 29 2018

Extensions

a(10)-a(11) from Jinyuan Wang, Feb 24 2020

Status

approved