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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A303942 Number of partitions of n into at most 1 copy of 1^2, 2 copies of 2^2, 3 copies of 3^2, ... .

Original entry on oeis.org

1, 1, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 0, 1, 1, 0, 1, 2, 2, 1, 1, 1, 1, 1, 1, 3, 3, 2, 1, 2, 2, 1, 2, 3, 4, 3, 3, 2, 2, 2, 2, 4, 4, 4, 3, 4, 3, 2, 3, 5, 7, 5, 5, 5, 6, 4, 3, 6, 8, 8, 5, 6, 6, 6, 6, 7, 9, 9, 10, 8, 8, 7, 8, 10, 11, 12, 10, 11, 10, 10, 9, 12, 15, 14, 14
Offset: 0

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Author

Seiichi Manyama, May 03 2018

Keywords

Examples

			   n |              | a(n)
-----+--------------+------
   1 | 1            |  1
   4 | 4            |  1
   5 | 4+1          |  1
   8 | 4+4          |  1
   9 | 9, 4+4+1     |  2
  10 | 9+1          |  1
  13 | 9+4          |  1
  14 | 9+4+1        |  1
  16 | 16           |  1
  17 | 16+1, 9+4+4  |  2
  18 | 9+9, 9+4+4+1 |  2
		

Crossrefs

Formula

G.f.: Product_{k>=1} (1-x^(k^2*(k+1)))/(1-x^(k^2)).

A094930 Triangle T(n,m) read by rows, defined by squaring a matrix with row entries 2+3*(m-1).

Original entry on oeis.org

4, 14, 25, 30, 65, 64, 52, 120, 152, 121, 80, 190, 264, 275, 196, 114, 275, 400, 462, 434, 289, 154, 375, 560, 682, 714, 629, 400, 200, 490, 744, 935, 1036, 1020, 860, 529, 252, 620, 952, 1221, 1400, 1462, 1380, 1127, 676, 310, 765, 1184, 1540, 1806, 1955, 1960
Offset: 1

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Author

Gary W. Adamson, Jun 17 2004

Keywords

Comments

Matrix square of the matrix B(n,m) = 2+3*(m-1), B containing the first terms of A016789
in its row n, n>0, 1<=m<=n.

Examples

			The matrix B starts as
  2 ;
  2,5 ;
  2,5,8 ;
  2,5,8,11 ;
  2,5,8,11,14 ;
and interpreting this as a lower triangular matrix, its square T = B^2 starts
  4;
  14,25;
  30,65,64;
  52,120,152,121;
		

Crossrefs

Programs

  • Maple
    A094930 := proc(n,m) (3*m-1)*(3*m+3*n-2)*(n+1-m)/2 ; end: seq(seq(A094930(n,m),m=1..n),n=1..20) ; # R. J. Mathar, Oct 09 2009

Formula

T(n,m) = sum_{k=m..n} B(n,k)*B(k,m) = (3*m-1)*(3*m+3*n-2)*(n+1-m)/2.
Row sums: sum_{m=1..n} T(n,m) = A024212(n).
G.f. as triangle: x*y*(4+2*x+13*x*y-16*x^2*y+x^2*y^2-4*x^3*y^2)/((1-x)*(1-x*y))^3. - Robert Israel, May 06 2019

Extensions

Edited and extended by R. J. Mathar, Oct 09 2009

A096037 Triangle T(n,m) = (3*n+3*m-2)*(n+1-m)/2 read by rows.

Original entry on oeis.org

2, 7, 5, 15, 13, 8, 26, 24, 19, 11, 40, 38, 33, 25, 14, 57, 55, 50, 42, 31, 17, 77, 75, 70, 62, 51, 37, 20, 100, 98, 93, 85, 74, 60, 43, 23, 126, 124, 119, 111, 100, 86, 69, 49, 26, 155, 153, 148, 140, 129, 115, 98, 78, 55, 29, 187, 185, 180, 172, 161, 147, 130, 110, 87, 61, 32
Offset: 1

Views

Author

Gary W. Adamson, Jun 17 2004

Keywords

Examples

			The triangle starts in row n=1 as
2;
7,5;
15,13,8;
26,24,19,11;
		

Crossrefs

Programs

  • Python
    def A096037(n,m):
        return (3*n+3*m-2)*(n+1-m)//2
    print( [A096037(n,m) for n in range(20) for m in range(1,n+1)] )
    # R. J. Mathar, Oct 11 2009

Formula

T(n,m) = (3*n+3*m-2)*(n+1-m)/2 .
T(n,m) = A094930(n,m)/(3*m-1).
T(n,1) = A005449(n).
T(n,n) = A016768(n-1).
Row sums: sum_{m=1..n} T(n,m) = n^2*(n+1) = A011379(n).

Extensions

Edited and extended, A-numbers corrected by R. J. Mathar, Oct 11 2009

A158497 Triangle T(n,k) formed by the coordination sequences and the number of leaves for trees.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 6, 12, 1, 4, 12, 36, 108, 1, 5, 20, 80, 320, 1280, 1, 6, 30, 150, 750, 3750, 18750, 1, 7, 42, 252, 1512, 9072, 54432, 326592, 1, 8, 56, 392, 2744, 19208, 134456, 941192, 6588344, 1, 9, 72, 576, 4608, 36864, 294912, 2359296, 18874368, 150994944, 1, 10, 90, 810, 7290, 65610, 590490, 5314410, 47829690, 430467210, 3874204890
Offset: 0

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Author

Thomas Wieder, Mar 20 2009

Keywords

Comments

Consider the k-fold Cartesian products CP(n,k) of the vector A(n) = [1, 2, 3, ..., n].
An element of CP(n,k) is a n-tuple T_t of the form T_t = [i_1, i_2, i_3, ..., i_k] with t=1, .., n^k.
We count members T of CP(n,k) which satisfy some condition delta(T_t), so delta(.) is an indicator function which attains values of 1 or 0 depending on whether T_t is to be counted or not; the summation sum_{CP(n,k)} delta(T_t) over all elements T_t of CP produces the count.
For the triangle here we have delta(T_t) = 0 if for any two i_j, i_(j+1) in T_t one has i_j = i_(j+1): T(n,k) = Sum_{CP(n,k)} delta(T_t) = Sum_{CP(n,k)} delta(i_j = i_(j+1)).
The test on i_j > i_(j+1) generates A158498. One gets the Pascal triangle A007318 if the indicator function tests whether for any two i_j, i_(j+1) in T_t one has i_j >= i_(j+1).
Use of other indicator functions can also calculate the Bell numbers A000110, A000045 or A000108.

Examples

			Array, A(n, k) = n*(n-1)^(k-1) for n > 1, A(n, k) = 1 otherwise, begins as:
  1,  1,   1,    1,     1,      1,       1,        1,        1, ... A000012;
  1,  1,   1,    1,     1,      1,       1,        1,        1, ... A000012;
  1,  2,   2,    2,     2,      2,       2,        2,        2, ... A040000;
  1,  3,   6,   12,    24,     48,      96,      192,      384, ... A003945;
  1,  4,  12,   36,   108,    324,     972,     2916,     8748, ... A003946;
  1,  5,  20,   80,   320,   1280,    5120,    20480,    81920, ... A003947;
  1,  6,  30,  150,   750,   3750,   18750,    93750,   468750, ... A003948;
  1,  7,  42,  252,  1512,   9072,   54432,   326592,  1959552, ... A003949;
  1,  8,  56,  392,  2744,  19208,  134456,   941192,  6588344, ... A003950;
  1,  9,  72,  576,  4608,  36864,  294912,  2359296, 18874368, ... A003951;
  1, 10,  90,  810,  7290,  65610,  590490,  5314410, 47829690, ... A003952;
  1, 11, 110, 1100, 11000, 110000, 1100000, 11000000, ............. A003953;
  1, 12, 132, 1452, 15972, 175692, 1932612, 21258732, ............. A003954;
  1, 13, 156, 1872, 22464, 269568, 3234816, 38817792, ............. A170732;
  ... ;
The triangle begins as:
  1
  1, 1;
  1, 2,  2;
  1, 3,  6,  12;
  1, 4, 12,  36,  108;
  1, 5, 20,  80,  320,  1280;
  1, 6, 30, 150,  750,  3750,  18750;
  1, 7, 42, 252, 1512,  9072,  54432, 326592;
  1, 8, 56, 392, 2744, 19208, 134456, 941192, 6588344;
  ...;
T(3,3) = 12 counts the triples (1,2,1), (1,2,3), (1,3,1), (1,3,2), (2,1,2), (2,1,3), (2,3,1), (2,3,2), (3,1,2), (3,1,3), (3,2,1), (3,2,3) out of a total of 3^3 = 27 triples in the CP(3,3).
		

Crossrefs

Array rows n: A170733 (n=14), ..., A170769 (n=50).
Columns k: A000012(n) (k=0), A000027(n) (k=1), A002378(n-1) (k=2), A011379(n-1) (k=3), A179824(n) (k=4), A101362(n-1) (k=5), 2*A168351(n-1) (k=6), 2*A168526(n-1) (k=7), 2*A168635(n-1) (k=8), 2*A168675(n-1) (k=9), 2*A170783(n-1) (k=10), 2*A170793(n-1) (k=11).
Diagonals k: A055897 (k=n), A055541 (k=n-1), A373395 (k=n-2), A379612 (k=n-3).
Sums: (-1)^n*A065440(n) (signed row).

Programs

  • Magma
    A158497:= func< n,k | k le 1 select n^k else n*(n-1)^(k-1) >;
    [A158497(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Mar 18 2025
    
  • Mathematica
    A158497[n_, k_]:= If[n<2 || k==0, 1, n*(n-1)^(k-1)];
    Table[A158497[n,k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Mar 18 2025 *)
  • SageMath
    def A158497(n,k): return n^k if k<2 else n*(n-1)^(k-1)
    print(flatten([[A158497(n,k) for k in range(n+1)] for n in range(13)])) # G. C. Greubel, Mar 18 2025

Formula

T(n, k) = (n-1)^(k-1) + (n-1)^k = n*A079901(n-1,k-1), k > 0.
Sum_{k=0..n} T(n,k) = (n*(n-1)^n - 2)/(n-2), n > 2.

Extensions

Edited by R. J. Mathar, Mar 31 2009
More terms added by G. C. Greubel, Mar 18 2025

A362007 Fourth Lie-Betti number of a path graph on n vertices.

Original entry on oeis.org

0, 0, 3, 16, 48, 107, 203, 347, 551, 828, 1192, 1658, 2242, 2961, 3833, 4877, 6113, 7562, 9246, 11188, 13412, 15943, 18807, 22031, 25643, 29672, 34148, 39102, 44566, 50573, 57157, 64353, 72197, 80726, 89978, 99992, 110808
Offset: 1

Views

Author

Samuel J. Bevins, Apr 05 2023

Keywords

Comments

Sequence T(n,4) in A360571.

Crossrefs

Cf. A360571 (path graph triangle), A088459 (second Lie-Betti number of path graphs), A361230.

Programs

  • Python
    def A362007(n):
        values = [0,0,3]
        for i in range(4, n+1):
            result = (i**4 + 18*i**3 - 97*i**2 + 174*i - 168)/24
            values.append(int(result))
        return values

Formula

a(1) = a(2) = 0, a(3) = 3, a(n) = (n^4 + 18*n^3 - 97*n^2 + 174*n - 168)/24 for n >= 4.
a(n) = A011379(n-3) + A006002(n-4) + A001105(n-3) + A056106(n-2) + A000027(n-3) + A000332(n-3) + A000217(n-5) + A000027(n-4) for n >= 5.
From Stefano Spezia, Mar 02 2025: (Start)
G.f.: x^2*(3 + x - 2*x^2 - 3*x^3 + 3*x^4 - x^5)/(1 - x)^5.
E.g.f.: (12*(6 + 4*x + x^2) - exp(x)*(72 - 24*x - 36*x^2 - 28*x^3 - x^4))/24. (End)

Extensions

a(34) and Python program corrected by Robert C. Lyons, Apr 17 2023

A368116 A(m, n) = lcm_{p in Partitions(n)} (Product_{r in p}(r + m)). Array read by ascending antidiagonals, for m, n >= 0.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 12, 6, 1, 4, 36, 24, 12, 1, 5, 80, 540, 720, 60, 1, 6, 150, 960, 6480, 1440, 360, 1, 7, 252, 5250, 134400, 136080, 60480, 2520, 1, 8, 392, 1512, 315000, 537600, 8164800, 120960, 5040, 1, 9, 576, 24696, 63504, 1575000, 32256000, 24494400, 3628800, 15120
Offset: 0

Views

Author

Peter Luschny, Dec 12 2023

Keywords

Comments

We say q is a 'm-shifted partition of n' if there is a partition p of n, p = (t1, t2, ..., tk) and q = (t1 + m, t2 + m, ..., tk + m), where m is a nonnegative integer. q is a partition of n + k*m.
Let P(n) denote the partitions of n and P_{m}(n) the m-shifted partitions of n. The product of a partition is the product of its parts, Prod(p) = p1*p2*...*pk if p = (p1, p2, ..., pk). Using this terminology, the definition can be written as A(m, n) = lcm_{p in P_{m}(n)} Prod(p).
With m = 0 the cumulative radical A048803 is computed, and with m = 1 the Hirzebruch numbers A091137.

Examples

			Array A(m, n) begins:
  [0] 1, 1,   2,     6,       12,        60,           360, ...  A048803
  [1] 1, 2,  12,    24,      720,      1440,         60480, ...  A091137
  [2] 1, 3,  36,   540,     6480,    136080,       8164800, ...  A368048
  [3] 1, 4,  80,   960,   134400,    537600,      32256000, ...
  [4] 1, 5, 150,  5250,   315000,   1575000,     330750000, ...
  [5] 1, 6, 252,  1512,    63504,   1905120,     880165440, ...
  [6] 1, 7, 392, 24696,  6914880, 532445760,  268352663040, ...
  [7] 1, 8, 576, 23040, 18247680, 145981440,  683193139200, ...
  [8] 1, 9, 810, 80190,  7217100, 844400700, 5851696851000, ...
.
Let m = 2 and n = 4. The partitions of 4 are [(4), (3,1), (2,2), (2,1,1), (1, 1, 1, 1)]. Thus A(2, 4) = lcm([6, 5*3, 4*4, 4*3*3, 3*3*3*3]) = 6480.
		

Crossrefs

Cf. A048803 (m=0), A091137 (m=1), A368048 (m=2).
Columns include: A000027, A011379.

Programs

  • SageMath
    def A(m, n): return lcm(product(r + m for r in p) for p in Partitions(n))
    for m in range(9): print([A(m, n) for n in range(7)])

A369415 Number A(n,k) of n X n Fishburn matrices with entries in the set {0,1,...,k}; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 12, 10, 0, 1, 4, 36, 264, 122, 0, 1, 5, 80, 2052, 19632, 3346, 0, 1, 6, 150, 9280, 505764, 4606752, 196082, 0, 1, 7, 252, 30750, 5684480, 511718148, 3311447232, 23869210, 0, 1, 8, 392, 83160, 39378750, 17672135680, 2088275673636, 7202118117504, 5939193962, 0
Offset: 0

Views

Author

Alois P. Heinz, Jan 22 2024

Keywords

Comments

Number of upper triangular n X n {0,1,...,k}-matrices with no zero rows or columns.

Examples

			A(2,3) = 3*3*4 = 36:
  [10] [10] [10]  [20] [20] [20]  [30] [30] [30]
  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]
.
  [11] [11] [11]  [21] [21] [21]  [31] [31] [31]
  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]
.
  [12] [12] [12]  [22] [22] [22]  [32] [32] [32]
  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]
.
  [13] [13] [13]  [23] [23] [23]  [33] [33] [33]
  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]  [ 1] [ 2] [ 3]
.
Square array A(n,k) begins:
  1,    1,       1,         1,           1,            1, ...
  0,    1,       2,         3,           4,            5, ...
  0,    2,      12,        36,          80,          150, ...
  0,   10,     264,      2052,        9280,        30750, ...
  0,  122,   19632,    505764,     5684480,     39378750, ...
  0, 3346, 4606752, 511718148, 17672135680, 305416893750, ...
  ...
		

Crossrefs

Columns k=0-3 give: A000007, A005321, A289314, A289315.
Rows n=0-3 give: A000012, A001477, A011379, A369423.
Main diagonal gives A369336.

Programs

  • Maple
    A:= (n, k)-> coeff(series(add(x^j*mul(((k+1)^i-1)/(1+x*
               ((k+1)^i-1)), i=1..j), j=0..n), x, n+1), x, n):
    seq(seq(A(n, d-n), n=0..d), d=0..10);

Formula

A(n,k) = [x^n] Sum_{j=0..n} x^j * Product_{i=1..j} ((k+1)^i-1)/(1+x*((k+1)^i-1)).

A132998 a(n) = n^4 - n^3 - n^2.

Original entry on oeis.org

0, -1, 4, 45, 176, 475, 1044, 2009, 3520, 5751, 8900, 13189, 18864, 26195, 35476, 47025, 61184, 78319, 98820, 123101, 151600, 184779, 223124, 267145, 317376, 374375, 438724, 511029, 591920, 682051, 782100, 892769
Offset: 0

Views

Author

Omar E. Pol, Nov 01 2007

Keywords

Examples

			a(7)=2009 because 7^4=2401, 7^3=343, 7^2=49 and we can write 2401-343-49=2009.
		

Crossrefs

Programs

Formula

a(n) = n^4 - n^3 - n^2.
G.f.: x*(-1+9*x+15*x^2+x^3)/(1-x)^5. - R. J. Mathar, Nov 14 2007

A202195 Number of (n+2) X 3 binary arrays avoiding patterns 001 and 101 in rows and columns.

Original entry on oeis.org

108, 240, 450, 756, 1176, 1728, 2430, 3300, 4356, 5616, 7098, 8820, 10800, 13056, 15606, 18468, 21660, 25200, 29106, 33396, 38088, 43200, 48750, 54756, 61236, 68208, 75690, 83700, 92256, 101376, 111078, 121380, 132300, 143856, 156066, 168948
Offset: 1

Views

Author

R. H. Hardin, Dec 14 2011

Keywords

Comments

Column 1 of A202202.

Examples

			Some solutions for n=10:
  0 0 0    0 0 0    1 0 0    1 0 0    1 0 0    0 1 1    0 1 1
  1 1 1    0 1 1    0 1 1    1 1 0    1 1 1    1 1 1    1 1 1
  1 1 0    0 1 1    0 1 1    0 1 0    1 1 1    1 1 1    1 1 1
  1 1 0    0 1 1    0 1 1    0 1 0    1 1 0    1 1 1    1 1 1
  1 1 0    0 1 1    0 1 0    0 1 0    1 0 0    1 1 1    1 1 1
  0 1 0    0 1 1    0 0 0    0 1 0    0 0 0    1 1 1    1 1 0
  0 1 0    0 1 1    0 0 0    0 1 0    0 0 0    1 1 0    1 0 0
  0 1 0    0 1 1    0 0 0    0 0 0    0 0 0    1 1 0    0 0 0
  0 1 0    0 1 0    0 0 0    0 0 0    0 0 0    0 1 0    0 0 0
  0 1 0    0 1 0    0 0 0    0 0 0    0 0 0    0 1 0    0 0 0
  0 1 0    0 0 0    0 0 0    0 0 0    0 0 0    0 0 0    0 0 0
  0 0 0    0 0 0    0 0 0    0 0 0    0 0 0    0 0 0    0 0 0
		

Crossrefs

Cf. A202202.

Formula

Empirical: a(n) = 3*(n+3)*(n+2)^2 = 3*A011379(n+2).
Conjectures from Colin Barker, Mar 03 2018: (Start)
G.f.: 6*x*(18 - 32*x + 23*x^2 - 6*x^3) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.
(End)

A286933 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of continued fraction 1/(1 - k*x/(1 - k*x^2/(1 - k*x^3/(1 - k*x^4/(1 - k*x^5/(1 - ...)))))).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 4, 2, 0, 1, 4, 9, 12, 3, 0, 1, 5, 16, 36, 32, 5, 0, 1, 6, 25, 80, 135, 88, 9, 0, 1, 7, 36, 150, 384, 513, 248, 15, 0, 1, 8, 49, 252, 875, 1856, 1971, 688, 26, 0, 1, 9, 64, 392, 1728, 5125, 9024, 7533, 1920, 45, 0, 1, 10, 81, 576, 3087, 11880, 30125, 43776, 28836, 5360, 78, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, May 16 2017

Keywords

Examples

			G.f. of column k: A(x) = 1 + k*x + k^2*x^2 + k^2*(k + 1)*x^3 + k^3*(k + 2)*x^4 + k^3*(k^2 + 3*k + 1)*x^5 + ...
Square array begins:
  1,  1,   1,    1,     1,     1,  ...
  0,  1,   2,    3,     4,     5,  ...
  0,  1,   4,    9,    16,    25,  ...
  0,  2,  12,   36,    80,   150,  ...
  0,  3,  32,  135,   384,   875,  ...
  0,  5,  88,  513,  1856,  5125,  ...
		

Crossrefs

Columns k=0..1 give: A000007, A005169.
Rows n=0..3 give: A000012, A001477, A000290, A011379.
Main diagonal gives A291274.
Cf. A286932.

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[1/(1 + ContinuedFractionK[-k x^i, 1, {i, 1, n}]), {x, 0, n}]][j - n], {j, 0, 11}, {n, 0, j}] // Flatten

Formula

G.f. of column k: 1/(1 - k*x/(1 - k*x^2/(1 - k*x^3/(1 - k*x^4/(1 - k*x^5/(1 - ...)))))), a continued fraction.
G.f. of column k (for k > 0): (Sum_{j>=0} (-k)^j*x^(j*(j+1))/Product_{i=1..j} (1 - x^i)) / (Sum_{j>=0} (-k)^j*x^(j^2)/Product_{i=1..j} (1 - x^i)).
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