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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. 18
 0, 1, 4, 9, 25, 100, 729, 2401, 9604, 71289, 235225, 940900, 6985449, 23049601, 92198404, 684502569, 2258625625, 9034502500, 67074266169, 221322261601, 885289046404, 6572593581849, 21687323011225, 86749292044900 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS 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 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 LINKS M. F. Hasler, Truncated squares, OEIS wiki, Jan 16 2012 FORMULA a(n) = A204518(n)^2. - M. F. Hasler, Jan 15 2012 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 EXAMPLE a(5) = 100 because 100 = 10^2 = 244 base 6 and 24 base 6 = 16 = 4^2. PROG (PARI) b=6; for(n=1, 2e9, issquare(n^2\b) & print1(n^2, ", ")) \\ M. F. Hasler, Jan 15 2012 CROSSREFS Cf. A023110. Sequence in context: A117678 A167045 A262753 * A025494 A087374 A081948 Adjacent sequences:  A055848 A055849 A055850 * A055852 A055853 A055854 KEYWORD base,nonn AUTHOR Henry Bottomley, Jul 14 2000 EXTENSIONS More terms added and offset changed to 1 by M. F. Hasler, Jan 16 2012 STATUS approved

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Last modified April 17 14:32 EDT 2021. Contains 343063 sequences. (Running on oeis4.)