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 A204521 Square root of floor(A055812(n) / 5). 4
 0, 0, 0, 1, 3, 4, 8, 21, 55, 72, 144, 377, 987, 1292, 2584, 6765, 17711, 23184, 46368, 121393, 317811, 416020, 832040, 2178309, 5702887, 7465176 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 COMMENTS Or: Numbers whose square yields another square when written in base 5. (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.) Base-5 analog of A031150 [base 10], A001353 [base 3], A001542 [base 2]. The square roots of A055812 are listed in A204520. LINKS FORMULA 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 PROG (PARI) b=5; for(n=1, 2e9, issquare(n^2\b) && print1(sqrtint(n^2\b), ", ")) CROSSREFS Cf. A055792, A055793, A204519, A204517, A204512, A204503 and A023110. Sequence in context: A129285 A051440 A101932 * A073313 A217248 A168382 Adjacent sequences:  A204518 A204519 A204520 * A204522 A204523 A204524 KEYWORD nonn AUTHOR M. F. Hasler, Jan 15 2012 STATUS approved

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Last modified March 29 20:20 EDT 2020. Contains 333117 sequences. (Running on oeis4.)