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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A116213 (2^(2^(2^n))-1)/(2^(2^n)+1).

Original entry on oeis.org

1, 3, 3855, 450552876409790643671482431940419874915447411150352389258589821042463539455
Offset: 0

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Author

Alexander Adamchuk, Apr 08 2007

Keywords

Comments

2^n+1 divides 2^(2^n)-1 iff n is a power of 2.

Crossrefs

Cf. A000215 = Fermat numbers: 2^(2^n)+1. Cf. A051179 = 2^(2^n)-1.

Programs

  • Mathematica
    Table[ (2^2^2^n - 1) / (2^2^n + 1), {n,0,3} ]

Formula

a(n) = (2^(2^(2^n))-1)/(2^(2^n)+1). a(n) = A051179(2^n)/A000215(n).

A116961 Numbers of the form 2^(2^k-1)-1, 2^(2^k-1), 2^(2^k)-1, 2^(2^k).

Original entry on oeis.org

0, 1, 2, 3, 4, 7, 8, 15, 16, 127, 128, 255, 256, 32767, 32768, 65535, 65536, 2147483647, 2147483648, 4294967295, 4294967296, 9223372036854775807, 9223372036854775808, 18446744073709551615, 18446744073709551616
Offset: 1

Views

Author

Henrik Lundquist (sploinker(AT)sploink.dk), Mar 30 2006

Keywords

Comments

The values are important in binary computer arithmetic.

Crossrefs

Extensions

Edited by Don Reble, Mar 31 2006

A162647 Numerators associated with denominators A000215(n) approximating the complementary Thue-Morse constant.

Original entry on oeis.org

2, 3, 10, 151, 38506, 2523490711, 10838310072981296746, 199931532107794273605284333428918544791, 68033174967769840440887906939858451149105560803546820641877549596291376780906
Offset: 0

Views

Author

Vladimir Shevelev, Jul 08 2009, Jul 14 2009

Keywords

Comments

If in the sequence of numbers N for which A010060(N+2^n)=1-A010060(N) the odious (evil) terms are
replaced by 1's (0's), we obtain a 2^(n+1)-periodic binary sequence. These are the post-period
binary (base-2) digits of the complementary Thue-Morse constant 1-A014571 = 0.58754596635989240221663...,
which has a continued fraction and convergents 3/5, 7/12, 10/17, 47/80, 151/257, 801/1365,...
The a(n) are numerators of the convergents selected with denominators taken from A000215.

Crossrefs

Formula

a(n)=A000215(n)-A162634(n). For n>=1, a(n+1)=1+(2^(2^n)-1)*a(n) = 1+A051179(n)*a(n).

Extensions

Edited by R. J. Mathar, Sep 23 2009
Previous Showing 41-43 of 43 results.