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.

A007886 Number of cycles induced by iterating the Gray-coding of an n-bit number: a(n+1) = a(n) + ( 2^n / C_n), where C_n = least power of 2 >= n (C_n is the length of the cycle).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 12, 20, 36, 52, 84, 148, 276, 532, 1044, 2068, 4116, 6164, 10260, 18452, 34836, 67604, 133140, 264212, 526356, 1050644, 2099220, 4196372, 8390676, 16779284, 33556500, 67110932, 134219796, 201328660, 335546388, 603981844
Offset: 0

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Author

Joe Culberson (joe(AT)cs.ualberta.ca)

Keywords

Crossrefs

Cf. A054243.

Programs

  • PARI
    f(n) = 2^(n-1-log(n+.5)\log(2)) \\ A054243
    a(n) = if (n<=1, n+1, a(n-1) + f(n-1));