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A204521 Square root of floor(A055812(n) / 5). 4

%I

%S 0,0,0,1,3,4,8,21,55,72,144,377,987,1292,2584,6765,17711,23184,46368,

%T 121393,317811,416020,832040,2178309,5702887,7465176

%N Square root of floor(A055812(n) / 5).

%C Or: Numbers whose square yields another square when written in base 5.

%C (For the first 3 terms, the above "base 5" interpretation is questionable, since they have only 1 digit in base 5. It is understood that dropping this digit yields 0.)

%C Base-5 analog of A031150 [base 10], A001353 [base 3], A001542 [base 2].

%C The square roots of A055812 are listed in A204520.

%F Empirical g.f.: x^4*(x^5+3*x^4+8*x^3+4*x^2+3*x+1) / ((x^4-4*x^2-1)*(x^4+4*x^2-1)). - _Colin Barker_, Sep 15 2014

%o (PARI) b=5;for(n=1,2e9,issquare(n^2\b) && print1(sqrtint(n^2\b),","))

%Y Cf. A055792, A055793, A204519, A204517, A204512, A204503 and A023110.

%K nonn

%O 1,5

%A _M. F. Hasler_, Jan 15 2012

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Last modified May 31 22:21 EDT 2020. Contains 334756 sequences. (Running on oeis4.)