cp's OEIS Frontend

A155714 Least number expressible as a^2 + p b^2 with positive integers a,b, for each prime p <= prime(n) = A000040(n).

%I A155714 #6 Jul 14 2012 11:32:23
%S A155714 3,12,36,144,144,4356,4356,4356,7056,17424,176400,2547216,2547216,
%T A155714 6290064,6780816,6780816,6780816,6780816,93315600,93315600,271986064,
%U A155714 271986064,271986064,271986064,271986064,308213136,308213136,308213136
%N A155714 Least number expressible as a^2 + p b^2 with positive integers a,b, for each prime p <= prime(n) = A000040(n).
%C A155714 a(n) > 10^9 for n >= 33. [From _Donovan Johnson_, Sep 29 2009]
%H A155714 Donovan Johnson, <a href="/A155714/b155714.txt">Table of n, a(n) for n=1..32</a>
%o A155714 (PARI) A155714(k,n=1) = { local(p); until( !n++, p=prime(k); until( !p=precprime(p-1), for( b=1, sqrtint((n-1)\p), issquare(n-p*b^2) & next(2)); next(2)); break);n}
%o A155714 t=1; for(k=1,30, print1(t=A155714(k,t),","))
%Y A155714 Cf. A155715, A028372, A000404, A154777, A092572, A097268, A154778, A155707-A155716, A155560-A155578.
%K A155714 nonn
%O A155714 1,1
%A A155714 _M. F. Hasler_, Feb 10 2009
%E A155714 a(12)-a(32) and b-file from _Donovan Johnson_, Sep 29 2009