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Least number with the prime signature of 2*prime(n) + 1.
5

%I #13 Nov 22 2016 21:48:41

%S 2,2,2,6,2,8,6,6,2,2,12,12,2,6,6,2,6,6,24,6,12,6,2,2,30,6,12,6,6,2,30,

%T 2,12,12,6,6,60,6,6,2,2,12,2,12,6,30,12,6,30,24,2,2,30,2,6,6,12,6,30,

%U 2,48,2,30,6,30,6,30,72,6,6,6,2,60,12,30,6,6,30,6,60,2,6,2,12,6,2,6,30,6,12,30,6,60,2,24,6,2,6,6,12,30,6,12,6,12,210,12

%N Least number with the prime signature of 2*prime(n) + 1.

%H Antti Karttunen, <a href="/A278230/b278230.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A046523(A072055(n)) = A046523(1 + 2*A000040(n)).

%t Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[ 2 Prime@ n + 1], {n, 120}] (* _Michael De Vlieger_, Nov 21 2016 *)

%o (Scheme) (define (A278230 n) (A046523 (+ 1 (* 2 (A000040 n)))))

%Y Cf. A000040, A046523, A072055.

%Y Cf. A072192 (positions of 2's), A005384.

%Y Cf. also A278227, A278228, A278229.

%K nonn

%O 1,1

%A _Antti Karttunen_, Nov 19 2016