

A055859


a(n) and floor(a(n)/7) are both squares; i.e., squares which remain squares when written in base 7 and last digit is removed.


15



0, 1, 4, 9, 64, 256, 2025, 16129, 64516, 514089, 4096576, 16386304, 130576329, 1040514049, 4162056196, 33165873225, 264286471744, 1057145886976, 8424001222569, 67127723308801, 268510893235204, 2139663144659049, 17050177433963584, 68200709735854336
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OFFSET

1,3


COMMENTS

Square roots of a(n) are listed in A204516, square roots of floor(a(n)/7) in A204517.  M. F. Hasler, Jan 16 2012


LINKS

Table of n, a(n) for n=1..24.
M. F. Hasler, Truncated squares, OEIS wiki, Jan 16 2012
Index to sequences related to truncating digits of squares.


FORMULA

a(n) = A204516(n)^2.  M. F. Hasler, Jan 16 2012
Empirical g.f.: x^2*(9*x^8+256*x^7+64*x^6270*x^5764*x^4191*x^3+9*x^2+4*x+1) / ((x1)*(x^2+x+1)*(x^6254*x^3+1)).  Colin Barker, Sep 15 2014


EXAMPLE

a(5) = 256 because 256 = 16^2 = 514 base 7 and 51 base 7 = 36 = 6^2.


CROSSREFS

Cf. A023110.
Sequence in context: A095175 A092396 A184877 * A162991 A062926 A069020
Adjacent sequences: A055856 A055857 A055858 * A055860 A055861 A055862


KEYWORD

base,nonn


AUTHOR

Henry Bottomley, Jul 14 2000


STATUS

approved



