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%I #11 Nov 22 2016 21:50:26
%S 1,2,4,2,8,6,2,6,16,12,2,6,2,4,6,2,32,6,6,6,6,2,30,6,2,4,12,2,24,24,6,
%T 12,64,30,2,30,2,2,6,30,2,16,6,6,6,24,2,6,6,2,12,2,30,24,30,2,30,48,2,
%U 12,12,6,120,2,128,30,2,6,24,2,30,6,6,6,6,2,60,24,12,6,6,6,48,30,6,120,4,2,30,48,6,180,2,6,24,30,2,2,6,2,60,72,6,6,6,48
%N Least number with the prime signature of A005187(n).
%H Antti Karttunen, <a href="/A278257/b278257.txt">Table of n, a(n) for n = 1..8193</a>
%F a(n) = A046523(A005187(n)).
%t f[n_] := If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Sort@ #[[All, -1]]] &@ FactorInteger@ n; Table[k = 1; While[f@ k != #, k++] &@ f[2 n - DigitCount[2 n, 2, 1]]; k, {n, 106}] (* or, faster *)
%t Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length# == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[2 n - DigitCount[2 n, 2, 1]], {n, 106}] (* _Michael De Vlieger_, Nov 21 2016 *)
%o (Scheme) (define (A278257 n) (A046523 (A005187 n)))
%Y Cf A005187, A046523.
%K nonn
%O 1,2
%A _Antti Karttunen_, Nov 19 2016
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