A071841 Number of primes == 5 mod 8 <= n.

0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7

Offset

1,13

Links

Table of n, a(n) for n=1..105.

Mathematica

Accumulate[Table[If[PrimeQ[n]&&Mod[n, 8]==5, 1, 0], {n, 110}]] (* Harvey P. Dale, Apr 28 2018 *)

Prog

(PARI) for(n=1, 200, print1(sum(i=1, n, if((i*isprime(i)-5)%8, 0, 1)), ", "))

Crossrefs

Sequence in context: A054900 A046042 A287866 * A355478 A097876 A177830

Adjacent sequences: A071838 A071839 A071840 * A071842 A071843 A071844

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 08 2002

Status

approved