cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A385608 a(n) = 2-adic valuation of A003266(n).

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 4, 4, 4, 5, 5, 5, 9, 9, 9, 10, 10, 10, 13, 13, 13, 14, 14, 14, 19, 19, 19, 20, 20, 20, 23, 23, 23, 24, 24, 24, 28, 28, 28, 29, 29, 29, 32, 32, 32, 33, 33, 33, 39, 39, 39, 40, 40, 40, 43, 43, 43, 44, 44, 44, 48, 48, 48, 49, 49, 49, 52, 52, 52, 53, 53, 53
Offset: 0

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Author

Paolo Xausa, Jul 04 2025

Keywords

Crossrefs

Partial sums of A337923.

Programs

  • Mathematica
    A385608[n_] := 2*# + Quotient[n, 6] - DigitSum[#, 2] & [Quotient[n, 3]];
    Array[A385608, 100, 0] (* or *)
    Join[{0}, Accumulate[IntegerExponent[Fibonacci[Range[99]], 2]]]

Formula

a(n) = 2*floor(n/3) + floor(n/6) - A000120(floor(n/3)) (formula by David Radcliffe at A385458).
a(n) = A007814(A003266(n)).
For n >= 1, a(n) = Sum_{k=1..n} A337923(k).
a(3*k) = a(3*k+1) = a(3*k+2), for k >= 0.
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