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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A268413 a(n) = Sum_{k = 0..n} (-1)^k*14^k.

Original entry on oeis.org

1, -13, 183, -2561, 35855, -501969, 7027567, -98385937, 1377403119, -19283643665, 269971011311, -3779594158353, 52914318216943, -740800455037201, 10371206370520815, -145196889187291409, 2032756448622079727, -28458590280709116177, 398420263929927626479
Offset: 0

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Author

Ilya Gutkovskiy, Feb 04 2016

Keywords

Comments

Alternating sum of powers of 14.
More generally, the ordinary generating function for the Sum_{k = 0..n} (-1)^k*m^k is 1/(1 + (m - 1)*x - m*x^2). Also, Sum_{k = 0..n} (-1)^k*m^k = ((-1)^n*m^(n + 1) + 1)/(m + 1).

Crossrefs

Cf. similar sequences of the type Sum_{k=0..n} (-1)^k*m^k: A059841 (m=1), A077925 (m=2), A014983 (m=3), A014985 (m=4), A014986 (m=5), A014987 (m=6), A014989 (m=7), A014990 (m=8), A014991 (m=9), A014992 (m=10), A014993 (m=11), A014994 (m=12), A015000 (m=13), this sequence (m=14), A239284 (m=15).

Programs

  • Magma
    I:=[1,-19]; [n le 2 select I[n] else -13*Self(n-1) +14*Self(n-2): n in [1..30]]; // G. C. Greubel, May 26 2018
  • Mathematica
    Table[((-1)^n 14^(n + 1) + 1)/15, {n, 0, 18}]
    LinearRecurrence[{-13, 14}, {1, -13}, 19]
    Table[Sum[(-1)^k*14^k, {k, 0, n}], {n, 0, 18}]
  • PARI
    x='x+O('x^30); Vec(1/(1 + 13*x - 14*x^2)) \\ G. C. Greubel, May 26 2018
    

Formula

G.f.: 1/(1 + 13*x - 14*x^2).
a(n) = ((-1)^n*14^(n + 1) + 1)/15.
a(n) = 1 - 14*a(n - 1) for n>0 and a(0)=1.
a(n) = Sum_{k = 0..n} A033999(k)*A001023(k).
Lim_{n -> infinity} a(n)/a(n + 1) = - 1/14.

A018084 Powers of fourth root of 14 rounded down.

Original entry on oeis.org

1, 1, 3, 7, 14, 27, 52, 101, 196, 379, 733, 1418, 2744, 5307, 10267, 19860, 38416, 74309, 143739, 278040, 537824, 1040332, 2012353, 3892567, 7529536, 14564655, 28172943, 54495951, 105413504, 203905179, 394421215, 762943322, 1475789056, 2854672519, 5521897022
Offset: 0

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Author

Keywords

Crossrefs

Cf. A011011.

Formula

a(n) = floor(A011011^n).
a(4n) = A001023(n). - R. J. Mathar, Mar 10 2025

A038218 Triangle whose (i,j)-th entry is binomial(i,j)*2^(i-j)*12^j (with i, j >= 0).

Original entry on oeis.org

1, 2, 12, 4, 48, 144, 8, 144, 864, 1728, 16, 384, 3456, 13824, 20736, 32, 960, 11520, 69120, 207360, 248832, 64, 2304, 34560, 276480, 1244160, 2985984, 2985984, 128, 5376, 96768, 967680, 5806080, 20901888, 41803776, 35831808
Offset: 0

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Author

Keywords

Comments

Examples

			From _Petros Hadjicostas_, Jul 23 2019: (Start)
Triangle T(i,j) (with rows i >= 0 and columns j >= 0) begins as follows:
    1;
    2,   12;
    4,   48,   144;
    8,  144,   864,   1728;
   16,  384,  3456,  13824,   20736;
   32,  960, 11520,  69120,  207360,   248832;
   64, 2304, 34560, 276480, 1244160,  2985984, 2985984;
  128, 5376, 96768, 967680, 5806080, 20901888, 41803776, 35831808;
  ... (End)
		

Crossrefs

Cf. A001021 (main diagonal), A001023 (row sums).

Programs

  • Magma
    /* As triangle */ [[Binomial(i,j)*2^(i-j)*12^j: j in [0..i]]: i in [0.. 15]]; // Vincenzo Librandi, Jul 24 2019
  • Mathematica
    Flatten[Table[Binomial[i, j] 2^(i - j) 12^j, {i, 0, 8}, {j, 0, i}]] (* Vincenzo Librandi, Jul 24 2019 *)

Formula

From Petros Hadjicostas, Jul 23 2019: (Start)
Bivariate g.f.: Sum_{i,j >= 0} T(i,j)*x^i*y^j = 1/(1 - 2*x * (1 + 6*y)).
G.f. for row i >= 0: 2^i * (1 + 6*y)^i.
G.f. for column j >= 0: (12*x)^j/(1 - 2*x)^(j+1).
(End)

Extensions

Name edited by Petros Hadjicostas, Jul 23 2019
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