A071840 Number of primes == 3 mod 8 <= n.

0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 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, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7

Offset

1,11

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

Accumulate[Table[If[PrimeQ[n]&&Mod[n, 8]==3, 1, 0], {n, 110}]] (* Harvey P. Dale, Apr 26 2025 *)

Prog

(PARI) for(n=1, 200, print1(sum(i=1, n, if((i*isprime(i)-3)%8, 0, 1)), ", "))

Crossrefs

Cf. A071839 (==1 mod 8), A071841 (==5 mod 8), A071842 (==7 mod 8).

Sequence in context: A086007 A108582 A345378 * A000193 A059939 A071842

Adjacent sequences: A071837 A071838 A071839 * A071841 A071842 A071843

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 08 2002

Status

approved