A094521 - OEIS

A094521

a(n) = gcd(n, A094457(n)).

1, 1, 2, 1, 2, 1, 4, 3, 2, 1, 4, 1, 2, 5, 8, 1, 6, 1, 4, 3, 2, 1, 8, 5, 2, 9, 4, 1, 10, 1, 16, 11, 2, 5, 12, 1, 2, 3, 8, 1, 6, 1, 4, 15, 2, 1, 16, 7, 10, 3, 4, 1, 18, 5, 8, 3, 2, 1, 20, 1, 2, 9, 32, 5, 22, 1, 4, 3, 10, 1, 24, 1, 2, 25, 4, 11, 6, 1, 16, 27, 2, 1, 12, 5, 2, 3, 8, 1, 30, 7, 4, 3, 2, 5, 32, 1

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OFFSET

2,3

LINKS

Michael De Vlieger, Table of n, a(n) for n = 2..10000

EXAMPLE

a(18) = gcd(18,12) = 6.

MATHEMATICA

f[n_] := Block[{g, h}, g[x_] := Flatten[Table[#1, {#2}] & @@@ FactorInteger@ x]; h[x_] := If[x == 2, 1, NextPrime[x, -1]]; If[n == 1, 1, Max[Times @@ MapAt[h, g[n], #] & /@ Range[Length@ g[n]]]]]; Table[GCD[i, f@ i], {i, 2, 74}] (* Michael De Vlieger, Jan 31 2015 *)

CROSSREFS

Cf. A094457 A094522.

Sequence in context: A072994 A332741 A052126 * A321757 A159272 A098372

Adjacent sequences: A094518 A094519 A094520 * A094522 A094523 A094524

KEYWORD

easy,nonn

AUTHOR

Marc LeBrun, May 06 2004

STATUS

approved