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 1-2 of 2 results.

A110571 Sums of rows of the triangle in A110570.

Original entry on oeis.org

1, 2, 4, 8, 12, 20, 22, 36, 38, 50, 54, 76, 66, 100, 94, 106, 116, 152, 128, 180, 154, 182, 194, 240, 192, 258, 250, 272, 262, 340, 264, 376, 330, 362, 374, 402, 352, 488, 442, 462, 428, 564, 444, 604, 518, 536, 586, 684, 534, 698, 620, 686, 662, 812, 658, 782
Offset: 0

Views

Author

Reinhard Zumkeller, Jul 28 2005

Keywords

Links

Programs

  • Mathematica
    T[n_, k_] := T[n, k] = If[Min[k, n - k] == 0, 1, 1 + T[n - Min[k, n - k], Min[k, n - k]]]; Table[Sum[T[n, k], {k, 0, n}], {n, 0, 50}] (* G. C. Greubel, Aug 31 2017 *)

A030451 a(2*n) = n, a(2*n+1) = n+2.

Original entry on oeis.org

0, 2, 1, 3, 2, 4, 3, 5, 4, 6, 5, 7, 6, 8, 7, 9, 8, 10, 9, 11, 10, 12, 11, 13, 12, 14, 13, 15, 14, 16, 15, 17, 16, 18, 17, 19, 18, 20, 19, 21, 20, 22, 21, 23, 22, 24, 23, 25, 24, 26, 25, 27, 26, 28, 27, 29, 28, 30, 29, 31, 30, 32, 31, 33, 32, 34, 33, 35, 34, 36, 35, 37, 36, 38, 37
Offset: 0

Views

Author

Daniel Smith (2true(AT)gte.net)

Keywords

Comments

Previous name was: Once started, this mixes the natural numbers and the natural numbers shifted by 1.
Smallest number of integer-sided squares needed to tile a 2 X n rectangle. a(5) = 4:
..._...
| | |_|
|_|___||. - _Alois P. Heinz, Jun 12 2013

Links

Crossrefs

Cf. A168361 (first differences), A198442 (partial sums).
Cf. A008619, A110570.
Row m=2 of A113881, A219158.
Essentially the same as A028242.

Programs

  • Maple
    a:= n-> iquo(n, 2, 'r') +[0, 2][r+1]:
seq(a(n), n=0..80);  # Alois P. Heinz, Jun 12 2013
  • Mathematica
    Riffle[# + 1, #] &@ Range[0, 37] (* or *)
Table[3/4 - (-1)^n 3/4 + n/2, {n, 0, 72}] (* or *)
CoefficientList[Series[(2 x - x^2)/((1 - x) (1 - x^2)), {x, 0, 72}], x] (* Michael De Vlieger, Apr 25 2016 *)
  • PARI
    a(n)=n\2+2*(n%2)

Formula

a(n) = 3/4 -(-1)^n*3/4 +n/2.
G.f.: (2*x-x^2)/((1-x)*(1-x^2)).
a(2n) = n, a(2n+1) = n+2.
a(n+2) = a(n)+1.
a(n) = -a(-3-n).
a(n) = A110570(n,2) for n>1. - Reinhard Zumkeller, Jul 28 2005
a(n) = (n+1)-a(n-1) with n>0, a(0)=0. - Vincenzo Librandi, Nov 18 2010
a(n) = Sum_{k=1..n} (-1)^(n+k)*(k+1). - Arkadiusz Wesolowski, Nov 23 2012
a(n+1) = (a(0) + a(1) + ... + a(n))/a(n) for n>0. This formula with different initial conditions produces A008619. - Ivan Neretin, Apr 25 2016
E.g.f.: (x*exp(x) + 3*sinh(x))/2. - Ilya Gutkovskiy, Apr 25 2016
Sum_{n>=1} (-1)^n/a(n) = 1. - Amiram Eldar, Oct 04 2022

Extensions

New name (using existing formula) from Joerg Arndt, Apr 26 2016
Showing 1-2 of 2 results.

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

Content is available under The OEIS End-User License Agreement.