A071823 Number of numbers x <= n with largest prime factor of the form 4k+3.

0, 0, 1, 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7, 7, 7, 7, 8, 9, 9, 10, 11, 12, 13, 13, 13, 14, 15, 15, 15, 16, 16, 17, 17, 18, 19, 19, 20, 20, 20, 20, 21, 22, 23, 23, 24, 25, 26, 27, 27, 27, 27, 27, 28, 29, 30, 31, 31, 32, 32, 32, 33, 34, 34, 34, 35, 36, 36, 37, 38, 39, 40, 40, 40, 40, 41

Offset

1,6

Comments

Conjecture : for n > 1000, a(n) - n/2 > sqrt(n).

Links

Table of n, a(n) for n=1..76.

Mathematica

Accumulate[Table[If[Mod[FactorInteger[n][[-1, 1]], 4]==3, 1, 0], {n, 80}]] (* Harvey P. Dale, Jun 29 2017 *)

Prog

(PARI) for(n=2, 200, print1(sum(i=2, n, if((component(component(factor(i), 1), omega(i))-3)%4, 0, 1)), ", "))

Crossrefs

Sequence in context: A194806 A229790 A156261 * A219642 A139338 A244229

Adjacent sequences: A071820 A071821 A071822 * A071824 A071825 A071826

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 07 2002

Extensions

Zero prepended by Harvey P. Dale, Jun 29 2017

Status

approved