A085972 - OEIS

A085972

Number of numbers <= n that are primes or not prime powers.

0, 1, 2, 2, 3, 4, 5, 5, 5, 6, 7, 8, 9, 10, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 20, 21, 22, 23, 24, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 54, 55, 56, 57, 58, 59, 60, 61

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OFFSET

1,3

COMMENTS

a(n) = Max{k: A085971(k)<=n};

a(n) = n-A085501(n) = A000720(n)+n-A065515(n) = A085970(n)+A000720(n).

LINKS

Table of n, a(n) for n=1..71.

MATHEMATICA

Accumulate[Table[If[PrimeQ[n]||(!PrimePowerQ[n]), 1, 0], {n, 80}]]-1 (* Harvey P. Dale, Oct 13 2022 *)

PROG

(Python)