A175027 Replace prime with its index!

0, 1, 1, 2, 4, 3, 6, 4, 8, 9, 10, 5, 12, 6, 14, 15, 16, 7, 18, 8, 20, 21, 22, 9, 24, 25, 26, 27, 28, 10, 30, 11, 32, 33, 34, 35, 36, 12, 38, 39, 40, 13, 42, 14, 44, 45, 46, 15, 48, 49, 50, 51, 52, 16, 54, 55, 56, 57, 58, 17, 60, 18, 62, 63, 64, 65, 66, 19, 68, 69, 70, 20, 72, 21

Offset

0,4

Links

Table of n, a(n) for n=0..73.

Formula

a(n)=n if n is nonprime otherwise a(n)=primepi(n).

Mathematica

Table[If[PrimeQ[n], PrimePi[n], n], {n, 0, 200}]

Crossrefs

Cf. A068519.

Sequence in context: A015049 A057956 A151734 * A269837 A308982 A182298

Adjacent sequences: A175024 A175025 A175026 * A175028 A175029 A175030

Keyword

nonn

Author

Zak Seidov, Nov 04 2009

Status

approved