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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A105810 Inverse of a Fibonacci-Pascal matrix A105809.

Original entry on oeis.org

1, -1, 1, 0, -2, 1, 1, 2, -3, 1, -2, -1, 5, -4, 1, 3, -1, -6, 9, -5, 1, -4, 4, 5, -15, 14, -6, 1, 5, -8, -1, 20, -29, 20, -7, 1, -6, 13, -7, -21, 49, -49, 27, -8, 1, 7, -19, 20, 14, -70, 98, -76, 35, -9, 1, -8, 26, -39, 6, 84, -168, 174, -111, 44, -10, 1, 9, -34, 65, -45, -78, 252, -342, 285, -155, 54, -11, 1
Offset: 0

Views

Author

Paul Barry, May 04 2005

Keywords

Comments

First column is A105811, row sums are A105812, antidiagonal sums are (-1)^n.

Examples

			The triangle T(n,m) begins:
n\m   0   1   2    3   4    5    6    7     8    9   10  11  12 13 ...
0:    1
1:   -1   1
2:    0  -2   1
3:    1   2  -3    1
4:   -2  -1   5   -4   1
5:    3  -1  -6    9  -5    1
6:   -4   4   5  -15  14   -6    1
7:    5  -8  -1   20 -29   20   -7    1
8:   -6  13  -7  -21  49  -49   27   -8     1
9:    7 -19  20   14 -70   98  -76   35    -9    1
10:  -8  26 -39    6  84 -168  174 -111    44  -10    1
11:   9 -34  65  -45 -78  252 -342  285  -155   54  -11   1
12: -10  43 -99  110  33 -330  594 -627   440 -209   65 -12   1
13:  11 -53 142 -209  77  363 -924 1221 -1067  649 -274  77 -13  1
... Reformatted and extended - _Wolfdieter Lang_, Oct 04 2014
-----------------------------------------------------------------------
Recurrence for T(n, 0) with row n-1 entries from Z-sequence (see a link given above): 3 = T(5, 0) = -(1*(-2) + 1*(-1) + 1*5 + 2*(-4) + 3*1) = 3.
		

Crossrefs

Cf. A105809, A105811, A105812, A248155 (alternating row sum). - Wolfdieter Lang, Oct 04 2014

Programs

  • Maple
    C := proc (n, k) if 0 <= k and k <= n then factorial(n)/(factorial(k)*factorial(n-k)) else 0 end if
    end proc:
    for n from 0 to 10 do
        seq((-1)^(n+k)*(C(n, n-k) - add(C(n-i, n-k-i), i = 2..n)), k = 0..n);
    end do; # Peter Bala, Mar 21 2018

Formula

Riordan array ((1+x-x^2)/(1+x)^2, x/(1+x)); Number triangle T(n, 0)=A105811(n), T(n, m)=-T(n-1, m-1)+T(n-1, m).
From Wolfdieter Lang, Oct 04 2014: (Start)
O.g.f. for row polynomials R(n,x) = sum(T(n,m)*x^m,m=0..n): (1 + z - z^2)/((1+z)*(1+(1-x)*z)) (Riordan property).
O.g.f. column m: x^m*(1 + x - x^2)/(1 + x)^(m+2), m >= 0.
The A-sequence of this Riordan triangle is [1, -1]. See the above given recurrence for T(n,m) for n>=1. The Z-sequence has o.g.f. -(1 - x^2)/(1 - x - x^2) and is -A132916(n+5) = -[1, 1, 1, 2, 3, 5, 8, 13, 21, 34,...]. See the W. Lang link under A006232 for Riordan A- and Z-sequences. (End)
T(n,k) = (-1)^(n+k)*(C(n, n-k) - Sum_{i = 2..n} C(n-i, n-k-i)), where C(n,k) = n!/(k!*(n-k)!) for 0 <= k <= n, otherwise 0. - Peter Bala, Mar 21 2018

A132915 a(0)=0; a(1)=1; a(n) = Sum_{k=1..[sqrt(n)]} a(n-k) for n>=2.

Original entry on oeis.org

0, 1, 1, 1, 2, 3, 5, 8, 13, 26, 47, 86, 159, 292, 537, 988, 1976, 3793, 7294, 14051, 27114, 52252, 100711, 194128, 374205, 748410, 1469706, 2887160, 5673609, 11153090, 21931975, 43115540, 84761374, 166635588, 327597567, 644042044, 1288084088
Offset: 0

Views

Author

Rick L. Shepherd, Sep 04 2007

Keywords

Comments

Lim n->infinity {a(n+1)/a(n)} = 2. Contrast with Fibonacci sequence. Also a(n+1)/a(n) = 2 iff n+1 is square.

Examples

			a(9) = a(6) + a(7) + a(8) = 5 + 8 + 13 = 26.
		

Crossrefs

Cf. A132916.

Formula

a(n) = sum a(n-k), k= 1 ... [sqrt(n)] for n>=2; a(0)=0; a(1)=1.
Showing 1-2 of 2 results.