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 A055872 a(n) and floor(a(n)/8) are both squares; i.e., squares that remain squares when written in base 8 and last digit is removed. 14
 0, 1, 4, 9, 36, 289, 1156, 9801, 39204, 332929, 1331716, 11309769, 45239076, 384199201, 1536796804, 13051463049, 52205852196, 443365544449, 1773462177796, 15061377048201, 60245508192804 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS For the first 3 terms which have only 1 digit in base 8, removing this digit is meant to yield 0. Base-8 analog of A055792 (base 2), A055793 (base 3), A055808 (base 4), A055812 (base 5), A055851 (base 6), A055859 (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. Index entries for linear recurrences with constant coefficients, signature (0,35,0,-35,0,1) FORMULA a(n) = A204514(n)^2. -  M. F. Hasler, Jan 15 2012 Empirical g.f.: -x^2*(4*x+1)*(9*x^4-26*x^2+1) / ((x-1)*(x+1)*(x^2-6*x+1)*(x^2+6*x+1)). - Colin Barker, Sep 15 2014 EXAMPLE a(5) = 289 because 289 = 17^2 = 441 base 8 and 44 base 8 = 36 = 6^2. MATHEMATICA Select[Range[0, 8*10^6]^2, IntegerQ[Sqrt[FromDigits[Most[ IntegerDigits[ #, 8]], 8]]]&] (* Harvey P. Dale, Aug 02 2016 *) PROG (PARI) b=8; for(n=1, 200, issquare(n^2\b) && print1(n^2, ", ")) \\ M. F. Hasler, Jan 15 2012 CROSSREFS Cf. A023110, A055792 (bisection). Sequence in context: A176830 A077211 A073977 * A066924 A251689 A249101 Adjacent sequences:  A055869 A055870 A055871 * A055873 A055874 A055875 KEYWORD base,nonn,easy AUTHOR Henry Bottomley, Jul 14 2000 EXTENSIONS More terms added and offset changed to 1 by M. F. Hasler, Jan 15 2012 STATUS approved

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Last modified February 17 23:35 EST 2020. Contains 332006 sequences. (Running on oeis4.)