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A055851 a(n) and floor(a(n)/6) are both squares; i.e., squares that remain squares when written in base 6 and last digit is removed.

%I A055851 #22 Jul 11 2015 00:20:32
%S A055851 0,1,4,9,25,100,729,2401,9604,71289,235225,940900,6985449,23049601,
%T A055851 92198404,684502569,2258625625,9034502500,67074266169,221322261601,
%U A055851 885289046404,6572593581849,21687323011225,86749292044900
%N A055851 a(n) and floor(a(n)/6) are both squares; i.e., squares that remain squares when written in base 6 and last digit is removed.
%C A055851 For the first 3 terms, the above "base 6" interpretation is questionable, since they have only 1 digit in base 6. It is understood that dropping this digit yields 0. - _M. F. Hasler_, Jan 15 2012
%C A055851 Base-6 analog of A055792 (base 2), A055793 (base 3), A055808 (base 4), A055812 (base 5), A204517 (base 7), A204503 (base 9) and A023110 (base 10). - _M. F. Hasler_, Jan 15 2012
%H A055851 M. F. Hasler, <a href="/wiki/M._F._Hasler/Truncated_squares">Truncated squares</a>, OEIS wiki, Jan 16 2012
%H A055851 <a href="/index/Sq#sqtrunc">Index to sequences related to truncating digits of squares</a>.
%F A055851 a(n) = A204518(n)^2. - _M. F. Hasler_, Jan 15 2012
%F A055851 Empirical g.f.: -x^2*(9*x^8+100*x^7+25*x^6-162*x^5-296*x^4-74*x^3+9*x^2+4*x+1) / ((x-1)*(x^2+x+1)*(x^6-98*x^3+1)). - _Colin Barker_, Sep 15 2014
%e A055851 a(5) = 100 because 100 = 10^2 = 244 base 6 and 24 base 6 = 16 = 4^2.
%o A055851 (PARI) b=6;for(n=1,2e9,issquare(n^2\b) & print1(n^2,",")) \\ _M. F. Hasler_, Jan 15 2012
%Y A055851 Cf. A023110.
%K A055851 base,nonn
%O A055851 1,3
%A A055851 _Henry Bottomley_, Jul 14 2000
%E A055851 More terms added and offset changed to 1 by _M. F. Hasler_, Jan 16 2012