cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A134607 Composite numbers such that the square root of the sum of squares of their prime factors is a prime.

This page as a plain text file.
%I A134607 #13 Jul 10 2013 20:40:28
%S A134607 48,320,486,3072,3150,6174,7128,7650,10890,11466,15000,18018,18810,
%T A134607 25578,27846,29400,30240,39546,40590,45056,45927,53010,54600,55062,
%U A134607 59202,73440,75582,77418,80910,85800,90552,92106,95238,96642,98838
%N A134607 Composite numbers such that the square root of the sum of squares of their prime factors is a prime.
%C A134607 Numbers included in A134605, but not in A134606. a(1)=48 is the minimal number with this property.
%H A134607 Hieronymus Fischer, <a href="/A134607/b134607.txt">Table of n, a(n) for n = 1..1000</a>
%e A134607 a(2)=320, since 320=2*2*2*2*2*2*5 and sqrt(6*2^2+5^2)=sqrt(49)=7.
%t A134607 sspfpQ[n_]:=PrimeQ[Sqrt[Total[Flatten[Table[#[[1]],{#[[2]]}]&/@ FactorInteger[ n]]^2]]]; upto=100000;With[{comps=Complement[ Range[ upto],Prime[ Range[PrimePi[upto]]]]},Select[comps,sspfpQ]] (* _Harvey P. Dale_, Jul 10 2013 *)
%Y A134607 Cf. A001597, A025475, A134333, A134344, A134376.
%Y A134607 Cf. A134600, A134602, A134605, A134611, A134616, A134618, A134620.
%K A134607 nonn
%O A134607 1,1
%A A134607 _Hieronymus Fischer_, Nov 11 2007
%E A134607 Minor edits by _Hieronymus Fischer_, Apr 19 2013