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a(n) = A008475(prime(n)-1).
4

%I #14 Dec 01 2020 03:28:44

%S 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,

%T 29,22,55,31,23,18,20,25,28,41,30,20,83,85,47,91,18,26,67,53,22,17,42,

%U 115,26,37,26,24,127,256,133,71,34,30,20,52,77,28,38,24,83,21,26,175,36

%N a(n) = A008475(prime(n)-1).

%H Nathaniel Johnston, <a href="/A081404/b081404.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 0 since 1 has no prime factor.

%e a(100) = A008475(541-1) = A008475(4*27*5) = 4+27+5 = 36.

%t 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}]

%Y Cf. A008475, A000142, A081402, A081403.

%K nonn

%O 1,2

%A _Labos Elemer_, Mar 31 2003