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A204504 A204512(n)^2 = floor[A055872(n)/8]: Squares such that appending some digit in base 8 yields another square.

%I A204504 #9 Mar 30 2012 17:23:05
%S A204504 0,0,0,1,4,36,144,1225,4900,41616,166464,1413721,5654884,48024900,
%T A204504 192099600,1631432881,6525731524,55420693056,221682772224,
%U A204504 1882672131025,7530688524100,63955431761796,255821727047184,2172602007770041,8690408031080164,73804512832419600
%N A204504 A204512(n)^2 = floor[A055872(n)/8]: Squares such that appending some digit in base 8 yields another square.
%C A204504 Base-8 analog of A202303.
%F A204504 a(n)=A204512(n)^2.
%F A204504 G.f. = x^4*(1 + 4*x + x^2 + 4*x^3)/(1 - 35*x^2 + 35*x^4 - x^6)
%o A204504 (PARI) b=8;for(n=1,2e9,issquare(n^2\b) & print1((n^2\b)","))
%o A204504 (PARI) a(n)=polcoeff(x^4*(1 + 4*x + x^2 + 4*x^3)/(1 - 35*x^2 + 35*x^4 - x^6+O(x^n)), n)
%Y A204504 See also A031149=sqrt(A023110) (base 10), A204502=sqrt(A204503) (base 9),
%Y A204504 A204514=sqrt(A055872) (base 8), A204516=sqrt(A055859) (base 7),
%Y A204504 A204518=sqrt(A055851) (base 6), A204520=sqrt(A055812) (base 5),
%Y A204504 A004275=sqrt(A055808) (base 4), A001075=sqrt(A055793) (base 3),
%Y A204504 A001541=sqrt(A055792) (base 2).
%K A204504 nonn,base
%O A204504 1,5
%A A204504 _M. F. Hasler_, Jan 15 2012