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 73 results. Next

A131774 2*A065941 - A049310.

Original entry on oeis.org

1, 2, 1, 1, 2, 1, 2, 0, 4, 1, 1, 2, 3, 4, 1, 2, -1, 8, 2, 6, 1, 1, 2, 4, 8, 7, 6, 1, 2, -2, 12, 0, 20, 6, 8, 1, 1, 2, 4, 12, 15, 20, 13, 8, 1, 2, -3, 16, -6, 42, 9, 40, 12, 10, 1
Offset: 1

Views

Author

Gary W. Adamson, Jul 14 2007

Keywords

Comments

Row sums = the Lucas numbers, A000032, starting (1, 3, 4, 7, 11, ...). Generally, N*A065941 - (N-1)*A049310 = triangles with row sums = Fibonacci-like sequences starting (1, (N+1), (N+1+1), ...). With N = 2, row sums of the triangle A131774 = (1, 3, 4, 7, ...).

Examples

			First few rows of the triangle:
  1;
  2,  1;
  1,  2,  1;
  2,  0,  4,  1;
  1,  2,  3,  4,  1;
  2, -1,  8,  2,  6,  1;
  1,  2,  4,  8,  7,  6,  1;
  ...
		

Crossrefs

Formula

2*A065941 - A049310 as infinite lower triangular matrices.

A065942 Central column of triangle A065941.

Original entry on oeis.org

1, 1, 3, 4, 15, 21, 84, 120, 495, 715, 3003, 4368, 18564, 27132, 116280, 170544, 735471, 1081575, 4686825, 6906900, 30045015, 44352165, 193536720, 286097760, 1251677700, 1852482996, 8122425444, 12033222880, 52860229080, 78378960360
Offset: 0

Views

Author

Len Smiley, Nov 29 2001

Keywords

Comments

When viewed as (1,1), (3,4), (15,21), ... this represents a shallow staircase on Pascal's triangle, arranged as a square array. - Paul Barry, Mar 11 2003
Also central column of triangle A011973 (taking rows with odd number of terms only). - John Molokach, Jul 08 2013
Interleaving of A005809 and A045721. - Bruce J. Nicholson, Apr 24 2018

Examples

			G.f. = 1 + x + 3*x^2 + 4*x^3 + 15*x^4 + 21*x^5 + 84*x^6 + 120*x^7 + ... - _Michael Somos_, Jun 23 2018
		

References

  • Thomas Koshy, "Fibonacci and Lucas Numbers with Applications", John Wiley and Sons, 2001 (Chapter 14)

Crossrefs

Cf. A065941 (complete triangle), A047749.

Programs

  • GAP
    List([0..40],n->Binomial(n+Int(n/2),n)); # Muniru A Asiru, Apr 28 2018
  • Mathematica
    Array[Binomial[# + Floor[#/2], #] &, 30, 0] (* Michael De Vlieger, Apr 27 2018 *)
  • PARI
    a(n) = binomial(n+n\2, n); \\ Altug Alkan, Apr 24 2018
    

Formula

a(n) = binomial(2n-floor((n+1)/2), floor(n/2)).
a(n+1) = Sum_{k=0..ceiling(n/2)} binomial(n+k, k). - Benoit Cloitre, Mar 06 2004
a(n) = binomial(n+floor(n/2), n). - Paul Barry, May 18 2004
a(n) = Sum_{k=0..floor(n/2)} binomial(n-1+k, k). - Paul Barry, Jul 06 2004
a(2n-1) = binomial(3n-3,n-1); a(2n) = binomial(3n-2,n-1). - John Molokach, Jul 08 2013
G.f.: A(x) = x*(d/dx)[log(S(x)-1)] = x*[(d/dx) S(x)]/[S(x)-1], where S(x) is the g.f. of A047749. - Vladimir Kruchinin, Jun 12 2014.
Conjecture: 8*n*(n-1)*a(n) -36*(n-1)*(n-3)*a(n-1) +6*(-9*n^2+18*n-14)*a(n-2) +27*(3*n-7)*(3*n-8)*a(n-3)=0. - R. J. Mathar, Jun 13 2014
0 = a(n)*(+281138850*a(n+2) +729089100*a(n+3) -77071527*a(n+4) -134472793*a(n+5)) +a(n+1)*(+15618825*a(n+2) -1650969*a(n+3) -9342280*a(n+4) -1729448*a(n+5)) +a(n+2)*(-19089675*a(n+2) -61394833*a(n+3) +6470716*a(n+4) +14929796*a(n+5)) +a(n+3)*(-1291668*a(n+3) +553572*a(n+4) +246032*a(n+5)) for all n in Z. - Michael Somos, Jun 23 2018

A131332 Triangle read by rows: A065941 * A097807.

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 2, -1, 2, 1, 1, 3, -2, 3, 1, 2, 1, 5, -4, 5, 0, 4, 2, 1, 8, -7, 8, -2, 7, 3, 3, 1, 13, -12, 13, -6, 12, 3, 7, 3, 1, 21, -20, 21, -13, 20, 1, 14, 6, 4, 1, 34, -33, 34, -25, 33, -5, 26, 9, 11, 4, 1, 55, -54, 55, -45, 54, -18, 46, 10, 25, 10, 5, 1, 89, -88, 89, -78, 88, -43, 79, 5, 51, 19, 16, 5, 1
Offset: 1

Views

Author

Gary W. Adamson, Jun 29 2007

Keywords

Comments

Row sums = Fibonacci numbers: (1, 1, 2, 3, 5, 8, ...).

Examples

			First few rows of the triangle are:
  1;
  0,  1;
  1,  0, 1;
  1,  0, 1,  1;
  2, -1, 2,  1, 1;
  3, -2, 3,  1, 2, 1;
  5, -4, 5,  0, 4, 2, 1;
  8, -7, 8, -2, 7, 3, 3, 1;
  ...
		

Crossrefs

Formula

A065941 * A000012(signed by columns, + - + - ...).

Extensions

a(47) = -20 corrected, name edited and more terms from Georg Fischer, Jun 05 2023

A131334 A000012(signed) * A065941.

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 0, 2, 1, 1, 0, 1, 2, 2, 2, 1, 1, 0, 3, 2, 4, 2, 1, 0, 1, 3, 3, 6, 4, 3, 1, 1, 0, 4, 3, 9, 6, 7, 3, 1, 0, 1, 4, 4, 12, 9, 13, 7, 4, 1
Offset: 1

Views

Author

Gary W. Adamson, Jun 29 2007

Keywords

Comments

Row sums = Fibonacci numbers.

Examples

			First few rows of the triangle are:
1;
0, 1;
1, 0, 1;
0, 1, 1, 1;
1, 0, 2, 1, 1;
0, 1, 2, 2, 2, 1;
1, 0, 3, 2, 4, 2, 1;
0, 1, 3, 3, 6, 4, 3, 1;
1, 0, 4, 3, 9, 6, 7, 3, 1;
...
		

Crossrefs

Formula

A000012(signed by columns, + - + -...) * A065941.

A131775 3*A065941 - 2*A049310.

Original entry on oeis.org

1, 3, 1, 1, 3, 1, 3, -1, 6, 1, 1, 3, 3, 6, 1, 3, -3, 12, 1, 9, 1, 1, 3, 3, 12, 8, 9, 1, 3, -5, 18, -5, 30, 6, 12, 1, 1, 3, 1, 18, 15, 30, 16, 12, 1, 3, -7, 24, -19, 63, 3, 60, 14, 15, 1
Offset: 1

Views

Author

Gary W. Adamson, Jul 14 2007

Keywords

Comments

Row sums = A000285, (a Fibonacci-like sequence) starting (1, 4, 5, 9, 14, 23, ...).

Examples

			Table begins:
  1;
  3,  1;
  1,  3,  1;
  3, -1,  6,  1;
  1,  3,  3,  6,  1;
  3, -3, 12,  1,  9,  1;
  1,  3,  3, 12,  8,  9,  1;
  3, -5, 18, -5, 30,  6, 12,  1;
  1,  3,  1, 18, 15, 30, 16, 12,  1;
  ...
		

Crossrefs

Formula

A131776 4*A065941 - 3*A049310.

Original entry on oeis.org

1, 4, 1, 1, 4, 1, 4, -2, 8, 1, 1, 4, 3, 8, 1, 4, -5, 16, 0, 12, 1, 1, 4, 2, 16, 9, 12, 1, 4, -8, 24, -10, 40, 6, 16, 1, 1, 4, -2, 24, 15, 40, 19, 16, 1, 4, -11, 32, -32, 84, -3, 80, 16, 20, 1
Offset: 1

Views

Author

Gary W. Adamson, Jul 14 2007

Keywords

Comments

Row sums = A022095, a Fibonacci-like sequence starting (1, 5, 6, 11, 17, 28, ...).

Examples

			First few rows of the triangle:
  1;
  4,  1;
  1,  4,  1;
  4, -2,  8,  1;
  1,  4,  3,  8,  1;
  4, -5, 16,  0, 12,  1;
  1,  4,  2, 16,  9, 12,  1;
  ...
		

Crossrefs

Formula

4*A065941 - 3*A049310 as infinite lower triangular matrices.

A131243 A065941^2 as an infinite lower triangular matrix.

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 5, 4, 4, 1, 8, 7, 10, 4, 1, 13, 12, 23, 12, 6, 1, 21, 20, 48, 29, 21, 6, 1, 34, 33, 96, 64, 62, 24, 8, 1, 55, 54, 185, 132, 160, 74, 36, 8, 1, 89, 88, 348, 261, 382, 200, 130, 40, 10, 1, 144, 143, 642, 500, 859, 492, 400, 150, 55, 10, 1
Offset: 0

Views

Author

Gary W. Adamson, Jun 22 2007

Keywords

Comments

Left border, Fibonacci numbers; next border to the right, (Fibonacci numbers - 1).

Examples

			First few rows of the triangle:
   1;
   2,  1;
   3,  2,   1;
   5,  4,   4,   1;
   8,  7,  10,   4,   1;
  13, 12,  23,  12,   6,   1;
  21, 20,  48,  29,  21,   6,   1;
  34, 33,  96,  64,  62,  24,   8,  1;
  55, 54, 185, 132, 160,  74,  36,  8,  1;
  89, 88, 348, 261, 382, 200, 130, 40, 10, 1;
		

Crossrefs

Cf. A065941, A131244 (row sums), A131245, A131246.

Extensions

Data and Example corrected by Jon E. Schoenfield, Feb 26 2022
More terms from Hakan Icoz, Jan 23 2023

A131777 5*A065941 - 4*A049310.

Original entry on oeis.org

1, 5, 1, 1, 5, 1, 5, -3, 10, 1, 1, 5, 3, 10, 1, 5, -7, 20, -1, 15, 1, 1, 5, 1, 20, 10, 15, 1, 5, -11, 30, -15, 50, 6, 20, 1, 1, 5, -5, 30, 15, 50, 22, 20, 1, 5, -15, 40, -45, 105, -9, 100, 18, 25, 1
Offset: 1

Views

Author

Gary W. Adamson, Jul 14 2007

Keywords

Comments

Row sums = A022096(n-1).

Examples

			First few rows of the triangle are:
1;
5, 1
1, 5, 1;
5, -3, 10, 1;
1, 5, 3, 10, 1;
5, -7, 20, -1, 15, 1;
1, 5, 1, 20, 10, 15, 1;
...
		

Crossrefs

Formula

5*A065941 - 4*A049310 as infinite lower triangular matrices.

Extensions

Corrected A-number in row sums reference R. J. Mathar, Jun 16 2009

A131778 6*A065941 - 5*A049310.

Original entry on oeis.org

1, 6, 1, 1, 6, 1, 6, -4, 12, 1, 1, 6, 3, 12, 1, 6, -9, 24, -2, 18, 1, 1, 6, 0, 24, 11, 18, 1, 6, -14, 36, -20, 60, 6, 24, 1, 1, 6, -8, 36, 15, 60, 25, 24, 1, 6, -19, 48, -58, 126, -15, 120, 20, 30, 1
Offset: 1

Views

Author

Gary W. Adamson, Jul 14 2007

Keywords

Comments

Row sums = A022097, a Fibonacci-like sequence starting (1, 7, 8, 15, 23, 38, ...).

Examples

			First few rows of the triangle:
  1;
  6,  1;
  1,  6,  1;
  6, -4, 12,  1;
  1,  6,  3, 12,  1;
  6, -9, 24, -2, 18,  1;
  1,  6,  0, 24, 11, 18,  1;
  ...
		

Crossrefs

Formula

6*A065941 - 5*A049310 as infinite lower triangular matrices.

A131402 2*A007318 - (A046854 + A065941 - A000012).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 4, 4, 1, 1, 6, 7, 6, 1, 1, 7, 14, 14, 7, 1, 1, 9, 20, 33, 20, 9, 1, 1, 10, 31, 56, 56, 31, 10, 1, 1, 12, 40, 97, 111, 97, 40, 12, 1, 1, 13, 55, 142, 217, 217, 142, 55, 13, 1, 1, 15, 67, 213, 358, 463, 358, 213, 67, 15, 1, 1, 16, 86, 287, 590, 841, 841, 590, 287, 86, 16, 1
Offset: 0

Views

Author

Gary W. Adamson, Jul 07 2007

Keywords

Comments

Row sums = A131403: (1, 2, 5, 10, 21, 44, 93, ...).

Examples

			First few rows of the triangle are:
  1;
  1,  1;
  1,  3,  1;
  1,  4,  4,  1;
  1,  6,  7,  6,  1;
  1,  7, 14, 14,  7,  1;
  1,  9, 20, 33, 20,  9,  1;
  1, 10, 31, 56, 56, 31, 10,  1;
  ...
		

Crossrefs

Row sums are A131403.

Programs

  • PARI
    T(n,k) = if(k <= n, 2*binomial(n, k) + 1 - binomial((n + k)\2, k) - binomial(n-(k+1)\2, k\2), 0) \\ Andrew Howroyd, Aug 09 2018

Formula

2*A007318 - (A046854 + A065941 - A000012) as infinite lower triangular matrices.
T(n,k) = 2*binomial(n, k) + 1 - binomial(floor((n + k)/2), k) - binomial(n-floor((k+1)/2), floor(k/2)). - Andrew Howroyd, Aug 09 2018

Extensions

Missing terms inserted and a(55) and beyond from Andrew Howroyd, Aug 09 2018
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