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A301944 Number of primes of the form b^2 + 1 for b <= 10^n that end in 7. 1
2, 13, 68, 560, 4418, 35953, 304340, 2636531, 23265760, 208241341, 1884492541 (list; graph; refs; listen; history; text; internal format)
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: A038144 A097977 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

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Last modified December 3 05:05 EST 2021. Contains 349445 sequences. (Running on oeis4.)