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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A291000 p-INVERT of (1,1,1,1,1,...), where p(S) = 1 - S - S^2 - S^3.

Original entry on oeis.org

1, 3, 9, 26, 74, 210, 596, 1692, 4804, 13640, 38728, 109960, 312208, 886448, 2516880, 7146144, 20289952, 57608992, 163568448, 464417728, 1318615104, 3743926400, 10630080640, 30181847168, 85694918912, 243312448256, 690833811712, 1961475291648, 5569190816256
Offset: 0

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Author

Clark Kimberling, Aug 22 2017

Keywords

Comments

Suppose s = (c(0), c(1), c(2),...) is a sequence and p(S) is a polynomial. Let S(x) = c(0)*x + c(1)*x^2 + c(2)*x^3 + ... and T(x) = (-p(0) + 1/p(S(x)))/x. The p-INVERT of s is the sequence t(s) of coefficients in the Maclaurin series for T(x). Taking p(S) = 1 - S gives the "INVERT" transform of s, so that p-INVERT is a generalization of the "INVERT" transform (e.g., A033453).
In the following guide to p-INVERT sequences using s = (1,1,1,1,1,...) = A000012, in some cases t(1,1,1,1,1,...) is a shifted version of the cited sequence:
p(S) t(1,1,1,1,1,...)
1 - S A000079
1 - S^2 A000079
1 - S^3 A024495
1 - S^4 A000749
1 - S^5 A139761
1 - S^6 A290993
1 - S^7 A290994
1 - S^8 A290995
1 - S - S^2 A001906
1 - S - S^3 A116703
1 - S - S^4 A290996
1 - S^3 - S^6 A290997
1 - S^2 - S^3 A095263
1 - S^3 - S^4 A290998
1 - 2 S^2 A052542
1 - 3 S^2 A002605
1 - 4 S^2 A015518
1 - 5 S^2 A163305
1 - 6 S^2 A290999
1 - 7 S^2 A291008
1 - 8 S^2 A291001
(1 - S)^2 A045623
(1 - S)^3 A058396
(1 - S)^4 A062109
(1 - S)^5 A169792
(1 - S)^6 A169793
(1 - S^2)^2 A024007
1 - 2 S - 2 S^2 A052530
1 - 3 S - 2 S^2 A060801
(1 - S)(1 - 2 S) A053581
(1 - 2 S)(1 - 3 S) A291002
(1 - S)(1 - 2 S)(1 - 3 S)(1 - 4 S) A291003
(1 - 2 S)^2 A120926
(1 - 3 S)^2 A291004
1 + S - S^2 A000045 (Fibonacci numbers starting with -1)
1 - S - S^2 - S^3 A291000
1 - S - S^2 - S^3 - S^4 A291006
1 - S - S^2 - S^3 - S^4 - S^5 A291007
1 - S^2 - S^4 A290990
(1 - S)(1 - 3 S) A291009
(1 - S)(1 - 2 S)(1 - 3 S) A291010
(1 - S)^2 (1 - 2 S) A291011
(1 - S^2)(1 - 2 S) A291012
(1 - S^2)^3 A291013
(1 - S^3)^2 A291014
1 - S - S^2 + S^3 A045891
1 - 2 S - S^2 + S^3 A291015
1 - 3 S + S^2 A136775
1 - 4 S + S^2 A291016
1 - 5 S + S^2 A291017
1 - 6 S + S^2 A291018
1 - S - S^2 - S^3 + S^4 A291019
1 - S - S^2 - S^3 - S^4 + S^5 A291020
1 - S - S^2 - S^3 + S^4 + S^5 A291021
1 - S - 2 S^2 + 2 S^3 A175658
1 - 3 S^2 + 2 S^3 A291023
(1 - 2 S^2)^2 A291024
(1 - S^3)^3 A291143
(1 - S - S^2)^2 A209917

Crossrefs

Programs

  • Mathematica
    z = 60; s = x/(1 - x); p = 1 - s - s^2 - s^3;
    Drop[CoefficientList[Series[s, {x, 0, z}], x], 1]  (* A000012 *)
    Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1]  (* A291000 *)

Formula

G.f.: (-1 + x - x^2)/(-1 + 4 x - 4 x^2 + 2 x^3).
a(n) = 4*a(n-1) - 4*a(n-2) + 2*a(n-3) for n >= 4.

A385178 Triangle T(n,k) read by rows in which the n-th diagonal lists the n-th differences of A001047, 0 <= k <= n.

Original entry on oeis.org

0, 1, 1, 3, 4, 5, 7, 10, 14, 19, 15, 22, 32, 46, 65, 31, 46, 68, 100, 146, 211, 63, 94, 140, 208, 308, 454, 665, 127, 190, 284, 424, 632, 940, 1394, 2059, 255, 382, 572, 856, 1280, 1912, 2852, 4246, 6305, 511, 766, 1148, 1720, 2576, 3856, 5768, 8620, 12866, 19171
Offset: 0

Views

Author

Paul Curtz, Jun 20 2025

Keywords

Examples

			Triangle begins:
    0;
    1,   1;
    3,   4,    5;
    7,  10,   14,   19;
   15,  22,   32,   46,   65;
   31,  46,   68,  100,  146,  211;
   63,  94,  140,  208,  308,  454,  665;
  127, 190,  284,  424,  632,  940, 1394, 2059;
  255, 382,  572,  856, 1280, 1912, 2852, 4246,  6305;
  511, 766, 1148, 1720, 2576, 3856, 5768, 8620, 12866, 19171;
  ...
		

Crossrefs

Columns k=0..2: A000225, A033484, A053209 (sans 1).
Diagonals: A001047, A027649, A053581 (sans 1), A291012 (sans 2).

Programs

  • Magma
    /* As triangle */ [[2^(n-k)*3^k - 2^k : k in [0..n]]: n in [0..9]]; // Vincenzo Librandi, Jun 27 2025
  • Maple
    T:= proc(n,k) option remember;
         `if`(n=k, 3^n-2^n, T(n, k+1)-T(n-1, k))
        end:
    seq(seq(T(n, k), k=0..n), n=0..10);  # Alois P. Heinz, Jun 24 2025
  • Mathematica
    t[n_, 0] := 3^n - 2^n; t[n_, k_] := t[n, k] = t[n + 1, k - 1] - t[n, k - 1]; Table[t[k, n - k], {n, 0, 9}, {k, 0, n}] // Flatten (* Amiram Eldar, Jun 20 2025 *)

Formula

T(n,n) = 3^n - 2^n = A001047(n).
T(n,k) = T(n,k+1) - T(n-1,k) for 0 <= k < n.
T(n,k) = 2^(n-k)*3^k - 2^k = A036561(n,k) - A059268(n,k).
T(2n,n) = A248216(n+1).
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