%I A055793
%S A055793 0,1,4,49,676,9409,131044,1825201,25421764,354079489,4931691076,68689595569,
%T A055793 956722646884,13325427460801,185599261804324
%N A055793 Numbers n such that n and floor[n/3] are both squares; i.e. squares which 
               remain squares when written in base 3 and last digit is removed.
%C A055793 Or, squares of the form 3n^2+1.
%F A055793 Conjecture: a(n)=3*A098301(n-2)+1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Jun 11 2009]
%e A055793 a(3) = 49 because 49 = 7^2 = 1211 base 3 and 121 base 3 = 16 = 4^2
%o A055793 (PARI) sq3nsqplus1(n) = { for(x=1,n, y = 3*x*x+1; \ print1(y" ") if(issquare(y),
               print1(y" ")) ) }
%Y A055793 Cf. A023110.
%Y A055793 Sequence in context: A067474 A053769 A086094 this_sequence A144656 A121275 
               A029991
%Y A055793 Adjacent sequences: A055790 A055791 A055792 this_sequence A055794 A055795 
               A055796
%K A055793 base,nonn
%O A055793 1,3
%A A055793 Henry Bottomley (se16(AT)btinternet.com), Jul 14 2000
%E A055793 More terms from Cino Hilliard (hillcino368(AT)gmail.com), Mar 01 2003