A081404 a(n) = A008475(prime(n)-1).

0, 2, 4, 5, 7, 7, 16, 11, 13, 11, 10, 13, 13, 12, 25, 17, 31, 12, 16, 14, 17, 18, 43, 19, 35, 29, 22, 55, 31, 23, 18, 20, 25, 28, 41, 30, 20, 83, 85, 47, 91, 18, 26, 67, 53, 22, 17, 42, 115, 26, 37, 26, 24, 127, 256, 133, 71, 34, 30, 20, 52, 77, 28, 38, 24, 83, 21, 26, 175, 36

Offset

1,2

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Example

a(1) = 0 since 1 has no prime factor.
a(100) = A008475(541-1) = A008475(4*27*5) = 4+27+5 = 36.

Mathematica

ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] ep[x_] := Table[Part[ffi[x], 2*w], {w, 1, lf[x]}] supo[x_] := Apply[Plus, ba[x]^ep[x]] Table[supo[w], {w, 1, 25}]

Crossrefs

Cf. A008475, A000142, A081402, A081403.

Sequence in context: A187325 A112233 A062249 * A255873 A141425 A081516

Adjacent sequences: A081401 A081402 A081403 * A081405 A081406 A081407

Keyword

nonn

Author

Labos Elemer, Mar 31 2003

Status

approved