cp's OEIS Frontend

A318885 If n = p^a * q^b * ... * r^c, with p < q < r primes, with nonzero exponents a, b, c, then a(n) = prime(1+p-p)^a * prime(1+q-p)^b * ... * prime(1+r-p)^c; a(1) = 1.

%I A318885 #8 Sep 24 2018 17:45:56
%S A318885 1,2,2,4,2,6,2,8,4,14,2,12,2,26,10,16,2,18,2,28,22,58,2,24,4,74,8,52,
%T A318885 2,42,2,32,46,106,10,36,2,122,62,56,2,78,2,116,20,158,2,48,4,98,94,
%U A318885 148,2,54,34,104,118,214,2,84,2,226,44,64,46,174,2,212,146,182,2,72,2,302,50,244,22,222,2,112,16,346,2,156,82,362,206,232,2
%N A318885 If n = p^a * q^b * ... * r^c, with p < q < r primes, with nonzero exponents a, b, c, then a(n) = prime(1+p-p)^a * prime(1+q-p)^b * ... * prime(1+r-p)^c; a(1) = 1.
%H A318885 Antti Karttunen, <a href="/A318885/b318885.txt">Table of n, a(n) for n = 1..16384</a>
%e A318885 For n = 10 = 2^1 * 5^1, a(n) = prime(1)^1 * prime(1+5-2)^1 = prime(1) * prime(4) = 2*7 = 14.
%e A318885 For n = 55 = 5^1 * 11^1, a(n) = prime(1)^1 * prime(1+11-5)^1 = prime(1) * prime(7) = 2*17 = 34.
%e A318885 For n = 90 = 2^1 * 3^2 * 5^1, a(n) = prime(1)^1 * prime(1+3-2)^2 * prime(1+5-2)^1 = 2^1 * 3^2 * 7^1 = 126.
%o A318885 (PARI) A318885(n) = if(1==n,n,my(f=factor(n),m=2^f[1,2],i=1); for(k=2,#f~,i += (f[k,1]-f[k-1,1]); m *= prime(i)^f[k,2]); (m));
%Y A318885 Cf. A318887 (rgs-transform), A318888.
%K A318885 nonn
%O A318885 1,2
%A A318885 _Antti Karttunen_, Sep 24 2018