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.

Showing 1-3 of 3 results.

A147675 Divide by 2, multiply by 4, repeat.

Original entry on oeis.org

10, 5, 20, 10, 40, 20, 80, 40, 160, 80, 320, 160, 640, 320, 1280, 640, 2560, 1280, 5120, 2560, 10240, 5120, 20480, 10240, 40960, 20480, 81920, 40960, 163840, 81920, 327680, 163840, 655360, 327680, 1310720, 655360, 2621440, 1310720, 5242880
Offset: 1

Views

Author

N. J. A. Sloane, Apr 21 2009

Keywords

Comments

A147675-A147678 are from a quiz that someone asked me to help them with.

Links

Crossrefs

Cf. A020714, A135530.

Programs

  • Mathematica
    LinearRecurrence[{0, 2}, {10, 5}, 50] (* Paolo Xausa, Jan 30 2024 *)

Formula

From R. J. Mathar, Apr 22 2009: (Start)
a(n) = 2*a(n-2) = 5*A135530(n-1).
G.f.: 5*x*(2+x)/(1-2*x^2). (End)
From Amiram Eldar, Feb 02 2024: (Start)
Sum_{n>=1} 1/a(n) = 3/5.
Sum_{n>=1} (-1)^n/a(n) = 1/5. (End)

Extensions

More terms from R. J. Mathar, Apr 22 2009

A147677 Subtract 5, add 8, repeat.

Original entry on oeis.org

7, 2, 10, 5, 13, 8, 16, 11, 19, 14, 22, 17, 25, 20, 28, 23, 31, 26, 34, 29, 37, 32, 40, 35, 43, 38, 46, 41, 49, 44, 52, 47, 55, 50, 58, 53, 61, 56, 64, 59, 67, 62, 70, 65, 73, 68, 76, 71, 79, 74, 82, 77, 85, 80, 88, 83, 91, 86, 94, 89, 97, 92, 100, 95, 103, 98, 106, 101, 109
Offset: 1

Views

Author

N. J. A. Sloane, Apr 21 2009

Keywords

Comments

A147675-A147678 are from a quiz that someone asked me to help them with.

Links

Programs

  • Mathematica
    LinearRecurrence[{1,1,-1},{7,2,10},80] (* Harvey P. Dale, Jan 16 2015 *)

Formula

From Zak Seidov, Apr 22 2009: (Start)
a(n) = a(n-2) + 3.
a(n) = (1/4)*(6*n + 9 - 13*(-1)^n). (End)
From R. J. Mathar, Apr 22 2009: (Start)
a(n) = a(n-1) + a(n-2) - a(n-3) = 3*n/2 + 9/4 + 13*(-1)^(n+1)/4.
G.f.: x*(7-5*x+x^2)/((1+x)*(x-1)^2). (End)

Extensions

More terms from Zak Seidov and R. J. Mathar, Apr 22 2009

A147676 Add 10, divide by 2, repeat.

Original entry on oeis.org

90, 100, 50, 60, 30, 40, 20, 30, 15, 25
Offset: 1

Views

Author

N. J. A. Sloane, Apr 21 2009

Keywords

Comments

A147675-A147678 are from a quiz that someone asked me to help them with.
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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