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 1-10 of 11 results. Next

A084219 Inverse binomial transform of A053088.

Original entry on oeis.org

1, -1, 4, -8, 20, -44, 100, -220, 484, -1052, 2276, -4892, 10468, -22300, 47332, -100124, 211172, -444188, 932068, -1951516, 4077796, -8505116, 17709284, -36816668, 76429540, -158451484, 328087780, -678545180, 1401829604
Offset: 0

Views

Author

Paul Barry, May 20 2003

Keywords

Comments

Contribution from Gary W. Adamson, Jan 05 2009: (Start)
Unsigned, starting with offset 1: generated from iterates of M * [1,1,1,...]
where M = a tridiagonal matrix with [0,1,1,1,...] as the main diagonal,
[1,1,1,...] as the uperdiagonal and [2,0,0,0,...] as the subdiagonal. (End)
Define a triangle via T(n,0) = T(n,n) = A001045(n) and T(r,c) = T(r-1,c-1) + T(r-1,c). The row sums of the triangle are s(n) = 0, 2, 4, 12, ... = 2*A059570(n), and their first differences are s(n+1)-s(n) = 2*|a(n)|. J. M. Bergot, May 15 2013

Programs

  • Mathematica
    LinearRecurrence[{-3,0,4},{1,-1,4},30] (* Harvey P. Dale, Dec 16 2016 *)

Formula

a(n) = (4 - 3*n*(-2)^(n-1) + 5*(-2)^n)/9.
a(n) = (1/4) + Sum_{k=0..n} (-2)^k*(k+3)/4.
G.f.: (1+x)^2/((1-x)(1+2x)^2).

A232603 a(n) = 2^n * Sum_{k=0..n} k^p*q^k, where p=2, q=-1/2.

Original entry on oeis.org

0, -1, 2, -5, 6, -13, 10, -29, 6, -69, -38, -197, -250, -669, -1142, -2509, -4762, -9813, -19302, -38965, -77530, -155501, -310518, -621565, -1242554, -2485733, -4970790, -9942309, -19883834, -39768509, -79536118
Offset: 0

Views

Author

Stanislav Sykora, Nov 27 2013

Keywords

Comments

The factor 2^n (i.e., |1/q|^n) is present to keep the values integer.
See also A232600 and references therein for integer values of q.

Examples

			a(3) = 2^3 * [0^2/2^0 - 1^2/2^1 + 2^2/2^2 - 3^2/2^3] = -5.
		

Crossrefs

Cf. A001045 (p=0,q=-1/2), A053088 (p=1,q=-1/2), A232604 (p=3,q=-1/2), A000225 (p=0,q=1/2), A000295 and A125128 (p=1,q=1/2), A047520 (p=2,q=1/2), A213575 (p=3,q=1/2), A232599 (p=3,q=-1), A232600 (p=1,q=-2), A232601 (p=2,q=-2), A232602 (p=3,q=-2).

Programs

  • Magma
    [((-1)^n*(2+12*n+9*n^2) -2^(n+1))/27: n in [0..30]]; // G. C. Greubel, Mar 31 2021
    
  • Maple
    A232603:= n-> ((-1)^n*(2+12*n+9*n^2) -2^(n+1))/27; seq(A232603(n), n=0..35); # G. C. Greubel, Mar 31 2021
  • Mathematica
    LinearRecurrence[{-1,3,5,2}, {0,-1,2,-5}, 35] (* G. C. Greubel, Mar 31 2021 *)
  • PARI
    a(n)=((-1)^n*(9*n^2+12*n+2)-2^(n+1))/27;
    
  • Sage
    [((-1)^n*(2+12*n+9*n^2) -2^(n+1))/27 for n in (0..30)] # G. C. Greubel, Mar 31 2021

Formula

a(n) = ((-1)^n*(9*n^2+12*n+2) - 2^(n+1))/27.
G.f.: x*(-1+x)/( (1-2*x)*(1+x)^3 ). - R. J. Mathar, Nov 23 2014
E.g.f.: (1/27)*(-2*exp(2*x) + (2 -21*x +9*x^2)*exp(-x)). - G. C. Greubel, Mar 31 2021
a(n) = - a(n-1) + 3*a(n-2) + 5*a(n-3) + 2*a(n-4). - Wesley Ivan Hurt, Mar 31 2021

A232604 a(n) = 2^n * Sum_{k=0..n} k^p*q^k, where p=3, q=-1/2.

Original entry on oeis.org

0, -1, 6, -15, 34, -57, 102, -139, 234, -261, 478, -375, 978, -241, 2262, 1149, 6394, 7875, 21582, 36305, 80610, 151959, 314566, 616965, 1247754, 2479883, 4977342, 9935001, 19891954, 39759519, 79546038, 159062285
Offset: 0

Views

Author

Stanislav Sykora, Nov 27 2013

Keywords

Comments

The factor 2^n (i.e., |1/q|^n) is present to make the values integers.
See also A232600 and references therein for integer values of q.
The same values with different signs are produced by a(n) = n^3 - 2*a(n). The signs are all positive until n = 15, with negative signs on values for all subsequent odd indices. - Richard R. Forberg, Feb 17 2014.

Examples

			a(3) = 2^3 * (0^3/2^0 - 1^3/2^1 + 2^3/2^2 - 3^3/2^3) = 0-4+16-27 = -15.
		

Crossrefs

Cf. A001045 (p=0,q=-1/2), A053088 (p=1,q=-1/2), A232603 (p=2,q=-1/2), A000225 (p=0,q=1/2), A000295 and A125128 (p=1,q=1/2), A047520 (p=2,q=1/2), A213575 (p=3,q=1/2), A232599 (p=3,q=-1), A232600 (p=1,q=-2), A232601 (p=2,q=-2), A232602 (p=3,q=-2).

Programs

  • Magma
    [(2^(n+1) + (-1)^n*(9*n^3 +18*n^2 +6*n -2))/27: n in [0..35]]; // G. C. Greubel, Mar 31 2021
    
  • Maple
    A232604:= n-> (2^(n+1) +(-1)^n*(9*n^3 +18*n^2 +6*n -2))/27; seq(A232604(n), n=0..30); # G. C. Greubel, Mar 31 2021
  • Mathematica
    LinearRecurrence[{-2,2,8,7,2}, {0,-1,6,-15,34}, 35] (* G. C. Greubel, Mar 31 2021 *)
  • PARI
    a(n)=(2^(n+1)+(-1)^n*(9*n^3+18*n^2+6*n-2))/27;
    
  • Sage
    [(2^(n+1) + (-1)^n*(9*n^3 +18*n^2 +6*n -2))/27 for n in (0..35)] # G. C. Greubel, Mar 31 2021

Formula

a(n) = (2^(n+1) + (-1)^n*(9*n^3+18*n^2+6*n-2))/27.
G.f.: x*(1-4*x+x^2) / ( (2*x-1)*(1+x)^4 ). - R. J. Mathar, Nov 23 2014
E.g.f.: (1/27)*(2*exp(2*x) - (2 +33*x -45*x^2 +9*x^3)*exp(-x)). - G. C. Greubel, Mar 31 2021
a(n) = - 2*a(n-1) + 2*a(n-2) + 8*a(n-3) + 7*a(n-4) + 2*a(n-5). - Wesley Ivan Hurt, Mar 31 2021

A077898 Expansion of (1 - x)^(-1)/(1 + x - 2*x^2).

Original entry on oeis.org

1, 0, 3, -2, 9, -12, 31, -54, 117, -224, 459, -906, 1825, -3636, 7287, -14558, 29133, -58248, 116515, -233010, 466041, -932060, 1864143, -3728262, 7456549, -14913072, 29826171, -59652314, 119304657, -238609284, 477218599, -954437166, 1908874365, -3817748696, 7635497427
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2002

Keywords

Comments

Partial sums of A077925 (signed Jacobsthal numbers). - Paul Barry, Aug 26 2003
The generalized (3,-2)-Padovan sequence p(3,-2;n). See the W. Lang link under A000931 with (A,B)=(3,-2). - Wolfdieter Lang, Jun 28 2010

Examples

			(3,-2)-Padovan combinatorics from the (3,2)-Morse code with weights -2 and 3 for 3-lines -- and 2-lines -, respectively (see the W. Lang link under A000931). n=5: two codes - -- and -- - with the weights (3^1)*(-2)^1 and (-2)^1*3^1, respectively, adding up to 2*(3)(-2) = -12 = a(5). - _Wolfdieter Lang_, Jun 28 2010
		

Crossrefs

Programs

Formula

G.f.: (1-x)^(-1)/(1+x-2*x^2).
a(n) = Sum_{k=0..n} Sum_{j=0..k} Sum_{i=0..j} binomial(j, i)*(-3)^i. - Paul Barry, Aug 26 2003
a(n) = (-1)^n * A053088(n). - R. J. Mathar, Aug 30 2008
From Colin Barker, Apr 21 2016: (Start)
a(n) = 3*a(n-2) - 2*a(n-3) for n>2.
a(n) = (5+(-1)^n*2^(2+n)+3*n)/9. (End)
E.g.f.: (4*exp(-2*x) + (5 + 3*x)*exp(x))/9. - Ilya Gutkovskiy, Apr 21 2016
a(n) = Sum_{k=0..n} (n+1-k)*(-2)^k. - Bruno Berselli, May 15 2018

A103196 a(n) = (1/9)(2^(n+3)-(-1)^n(3n-1)).

Original entry on oeis.org

1, 2, 3, 8, 13, 30, 55, 116, 225, 458, 907, 1824, 3637, 7286, 14559, 29132, 58249, 116514, 233011, 466040, 932061, 1864142, 3728263, 7456548, 14913073, 29826170, 59652315, 119304656, 238609285, 477218598, 954437167
Offset: 0

Views

Author

Creighton Dement, Mar 18 2005

Keywords

Comments

A floretion-generated sequence relating to the Jacobsthal sequence A001045 as well as to A095342 (Number of elements in n-th string generated by a Kolakoski(5,1) rule starting with a(1)=1). (a(n)) may be seen as the result of a certain transform of the natural numbers (see program code).
Floretion Algebra Multiplication Program, FAMP Code: 4jesleftforseq[A*B] with A = + 'i + 'j + i' + j' + 'ii' + 'jj' + 'ij' + 'ji' + e and B = - .25'i + .25'j + .25'k + .25i' - .25j' + .25k' - .25'ii' + .25'jj' + .25'kk' + .25'ij' + .25'ik' + .25'ji' + .25'jk' - .25'ki' - .25'kj' - .25e; 1vesforseq[A*B](n) = n, ForType: 1A.

Crossrefs

Programs

  • Mathematica
    Table[(2^(n+3)-(-1)^n (3n-1))/9,{n,0,30}] (* or *) LinearRecurrence[ {0,3,2},{1,2,3},40] (* Harvey P. Dale, Jul 09 2018 *)

Formula

G.f. (2x+1)/((1-2x)(x+1)^2); Superseeker results: a(n) + a(n+1) = A001045(n+3); a(n+1) - a(n) = A095342(n+1); a(n+2) - a(n+1) - a(n) = A053088(n+1) = A034299(n+1) - A034299(n); a(n) + 2a(n+1) + a(n+2) = 2^(n+3); a(n+2) - 2a(n+1) + a(n) = A053088(n+1) - A053088(n); a(n+2) - a(n) = A001045(n+4) - A001045(n+3) = A052953(n+3) - A052953(n+2) = A026644(n+2) - A026644(n+1);
a(n)=sum{k=0..n+2, (-1)^(n-k)*C(n+2, k)phi(phi(3^k))}; a(n)=sum{k=0..n+2, (-1)^(n-k)*C(n+2, k)(2*3^k/9+C(1, k)/3+4*C(0, k)/9)}; a(n)=sum{k=0..n+2, J(n-k+3)((-1)^(k+1)-2C(1, k)+4C(0, k))} where J(n)=A001045(n); a(n)=A113954(n+2). - Paul Barry, Nov 09 2005

A172285 a(n) = (5*2^n - 5*(-1)^n - 3*n*(-1)^n) / 9.

Original entry on oeis.org

0, 2, 1, 6, 7, 20, 33, 74, 139, 288, 565, 1142, 2271, 4556, 9097, 18210, 36403, 72824, 145629, 291278, 582535, 1165092, 2330161, 4660346, 9320667, 18641360, 37282693, 74565414, 149130799, 298261628, 596523225, 1193046482, 2386092931, 4772185896
Offset: 0

Views

Author

Paul Curtz, Jan 30 2010

Keywords

Crossrefs

Programs

  • Magma
    [(5*2^n - 5*(-1)^n - 3*n*(-1)^n) / 9: n in [0..40]]; // Vincenzo Librandi, Aug 05 2011
    
  • Maple
    A172295 := proc(n) (5*2^n - 5*(-1)^n - 3*n*(-1)^n) / 9 ; end proc: seq(A172295(n), n=0..100) ; # R. J. Mathar, Feb 02 2010
  • Mathematica
    Table[(5*2^n - 5*(-1)^n - 3*n*(-1)^n)/9, {n, 0, 40}] (* Wesley Ivan Hurt, Aug 27 2015 *)
  • PARI
    first(m)=vector(m,i,i--;(5*2^i -5*(-1)^i - 3*i*(-1)^i ) / 9) \\ Anders Hellström, Aug 27 2015

Formula

a(n) = 3*a(n-2) + 2*a(n-3), n>2.
a(n+1) = 2*a(n) + (-1)^n * (2+n).
a(n) = A053088(n-1) + A001045(n), n>0.
a(n) = A000079(n) - A053088(n).
a(2n) = A141291(n). a(2n+1) = 2*A164044(n).
G.f.: x*(2+x)/( (1-2*x)*(1+x)^2 ).

Extensions

Definition replaced by explicit formula; g.f. added - R. J. Mathar, Feb 02 2010

A176737 Expansion of 1 / (1-4*x^2-3*x^3). (4,3)-Padovan sequence.

Original entry on oeis.org

1, 0, 4, 3, 16, 24, 73, 144, 364, 795, 1888, 4272, 9937, 22752, 52564, 120819, 278512, 640968, 1476505, 3399408, 7828924, 18027147, 41513920, 95595360, 220137121, 506923200, 1167334564, 2688104163, 6190107856, 14254420344, 32824743913, 75588004944, 174062236684
Offset: 0

Views

Author

Wolfdieter Lang, Jun 26 2010

Keywords

Comments

See A000931 (Padovan), and the W. Lang link given there.

Crossrefs

Cf. A053088 ((3,2)-Padovan).

Programs

  • Mathematica
    CoefficientList[Series[1/(1-4*x^2-3*x^3),{x,0,40}],x] (* or *) LinearRecurrence[ {0,4,3},{1,0,4},40] (* Harvey P. Dale, Jan 21 2013 *)
  • PARI
    Vec(1 / ((1 + x)*(1 - x - 3*x^2)) + O(x^40)) \\ Colin Barker, Dec 25 2017

Formula

O.g.f.: 1/((1-x-3*x^2)*(1+x)) = (2-3*x)/(1-x-3*x^2) -1/(1+x).
a(n) = 2*b(n) - 3*b(n-1) - (-1)^n, n>=0, with b(n):=A006130(n) ((1,3)-Fibonacci), b(-1):=0.
From Wolfdieter Lang, Aug 26 2010: (Start)
a(n) = a(n-1) + 3*a(n-2) + (-1)^n, n>=2, a(0)=1, a(1)=0.
Due to the identity for the o.g.f. A(x): A(x)= x*(1 + 3*x)*A(x) + 1/(1+x).
(This recurrence was observed by Gary Detlefs in an Aug 24 2010 email to the author.)
(End)
a(n) = 4*a(n-2) + 3*a(n-3) for n>2. - Harvey P. Dale, Jan 21 2013
a(n) = (-1)^(n+1)*A140165(n+2)-(-1)^n. - R. J. Mathar, Apr 22 2013
a(n) = ((-1)^(1+n) + (2^(-n)*((-2+sqrt(13))*(1+sqrt(13))^n + (1-sqrt(13))^n*(2+sqrt(13)))) / sqrt(13)). - Colin Barker, Dec 25 2017

A113678 Sequence array for A078008.

Original entry on oeis.org

1, 0, 1, 2, 0, 1, 2, 2, 0, 1, 6, 2, 2, 0, 1, 10, 6, 2, 2, 0, 1, 22, 10, 6, 2, 2, 0, 1, 42, 22, 10, 6, 2, 2, 0, 1, 86, 42, 22, 10, 6, 2, 2, 0, 1, 170, 86, 42, 22, 10, 6, 2, 2, 0, 1, 342, 170, 86, 42, 22, 10, 6, 2, 2, 0, 1, 682, 342, 170, 86, 42, 22, 10, 6, 2, 2, 0, 1, 1366, 682, 342, 170, 86
Offset: 0

Views

Author

Paul Barry, Nov 04 2005

Keywords

Comments

Row sums are A001045(n+1). Diagonal sums are A053088. Inverse is A113680.

Examples

			Triangle begins
1;
0, 1;
2, 0, 1;
2, 2, 0, 1;
6, 2, 2, 0, 1;
10, 6, 2, 2, 0, 1;
22, 10, 6, 2, 2, 0, 1;
		

Formula

Riordan array ((1-x)/(1-x-2x^2), x); Number triangle T(n, k)=if(k<=n, (2^(n-k)+2(-1)^(n-k))/3, 0); T(n, k)=sum{i=0..n, C(n-i, k)C(k, n-i)(2^i+2(-1)^i)/3}.

A366987 Triangle read by rows: T(n, k) = -(2^(n - k)*(-1)^n + 2^k + (-1)^k)/3.

Original entry on oeis.org

-1, 0, 0, -2, -1, -2, 2, 1, -1, -2, -6, -3, -3, -3, -6, 10, 5, 1, -1, -5, -10, -22, -11, -7, -5, -7, -11, -22, 42, 21, 9, 3, -3, -9, -21, -42, -86, -43, -23, -13, -11, -13, -23, -43, -86, 170, 85, 41, 19, 5, -5, -19, -41, -85, -170, -342, -171, -87, -45, -27, -21, -27, -45, -87, -171, -342
Offset: 0

Views

Author

Paul Curtz and Thomas Scheuerle, Oct 31 2023

Keywords

Examples

			Triangle T(n, k) starts:
   -1
    0   0
   -2  -1  -2
    2   1  -1  -2
   -6  -3  -3  -3  -6
   10   5   1  -1  -5 -10
  -22 -11  -7  -5  -7 -11 -22
   42  21   9   3  -3  -9 -21 -42
   ...
Note the symmetrical distribution of the absolute values of the terms in each row.
		

Crossrefs

Rows sums: -A282577(n+2), if the conjectures from Colin Barker in A282577 are true.
First column: -(-1)^n * A078008(n).
Second column: (-1)^n * A001045(n).
Third column: -A140966(n).
Fourth column: (-1)^n * A155980(n+2).

Programs

  • Maple
    T := (n, k) -> -(2^(n-k)*(-1)^n + 2^k + (-1)^k)/3:
    seq(seq(T(n, k), k = 0..n), n = 0..10);  # Peter Luschny, Nov 02 2023
  • Mathematica
    A366987row[n_]:=Table[-(2^(n-k)(-1)^n+2^k+(-1)^k)/3,{k,0,n}];Array[A366987row,15,0] (* Paolo Xausa, Nov 07 2023 *)
  • PARI
    T(n, k) = (-2^(k+1) + 2*(-1)^(k+1) + (-1)^(n+1)*2^(1+n-k))/6 \\ Thomas Scheuerle, Nov 01 2023

Formula

T(n, 0) = -((-2)^n + 2)/3.
T(n, k+1) - T(n, k) = T(n-1, k) + (-1)^k.
T(2*n+1, n) = A001045(n).
T(2*n+1, n+1) = -A001045(n).
T(2*n, n+1) = -A048573(n-1), for n > 0.
Note that the definition of T extends to negative parameters:
T(2*n-2, n-1) = -A001045(n).
-2^n*Sum_{k=0..n} (-1)^k*T(-n, -k) = A059570(n+1).
-4^n*Sum_{k=0..2*n} T(-2*n, -k) = A020989(n).
-Sum_{k=0..n} (-1)^k*T(n, k) = A077898(n). See also A053088.
Sum_{k = 0..2*n} |T(2*n, k)| = (4^(n+1) - 1)/3.
Sum_{k = 0..2*n+1} |T(2*n+1, k)| = (1 + (-1)^n - 2^(2 + n) + 2^(1 + 2*n))/3.
G.f.: (-1 - x + x*y)/((1 - x)*(1 + 2*x)*(1 + x*y)*(1 - 2*x*y)). - Stefano Spezia, Nov 03 2023

Extensions

a(42) corrected by Paolo Xausa, Nov 07 2023

A099095 Riordan array (1,3+2x).

Original entry on oeis.org

1, 0, 3, 0, 2, 9, 0, 0, 12, 27, 0, 0, 4, 54, 81, 0, 0, 0, 36, 216, 243, 0, 0, 0, 8, 216, 810, 729, 0, 0, 0, 0, 96, 1080, 2916, 2187, 0, 0, 0, 0, 16, 720, 4860, 10206, 6561, 0, 0, 0, 0, 0, 240, 4320, 20412, 34992, 19683, 0, 0, 0, 0, 0, 32, 2160, 22680, 81648, 118098, 59049, 0, 0
Offset: 0

Views

Author

Paul Barry, Sep 25 2004

Keywords

Comments

Row sums are A007482. Diagonal sums are A053088. The Riordan array (1,s+tx) defines T(n,k)=binomial(k,n-k)s^k(t/s)^(n-k). The row sums satisfy a(n)=s*a(n-1)+t*a(n-2) and the diagonal sums satisfy a(n)=s*a(n-2)+t*a(n-3).

Examples

			Rows begin {1}, {0,3}, {0,2,9}, {0,0,12,27}, {0,0,4,54,81},...
		

Crossrefs

Cf. A038220.

Formula

Number triangle T(n, k)=binomial(k, n-k)3^k*(2/3)^(n-k); Columns have g.f. (3x+2x^2)^k.
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