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 1-7 of 7 results.

A111536 Triangular matrix T, read by rows, that satisfies: SHIFT_LEFT(column 0 of T^p) = p*(column p+2 of T), or [T^p](m,0) = p*T(p+m,p+2) for all m>=1 and p>=-2.

Original entry on oeis.org

1, 1, 1, 4, 2, 1, 22, 8, 3, 1, 148, 44, 14, 4, 1, 1156, 296, 84, 22, 5, 1, 10192, 2312, 600, 148, 32, 6, 1, 99688, 20384, 4908, 1156, 242, 44, 7, 1, 1069168, 199376, 44952, 10192, 2084, 372, 58, 8, 1, 12468208, 2138336, 454344, 99688, 20012, 3528, 544, 74, 9, 1
Offset: 0

Views

Author

Paul D. Hanna, Aug 06 2005

Keywords

Comments

Column 0 equals A111529 (related to log of factorial series).
Column 2 (A111538) equals SHIFT_LEFT(column 0 of log(T)), where the matrix logarithm, log(T), equals the integer matrix A111541.

Examples

			SHIFT_LEFT(column 0 of T^-2) = -2*(column 0 of T);
SHIFT_LEFT(column 0 of T^-1) = -1*(column 1 of T);
SHIFT_LEFT(column 0 of log(T)) = column 2 of T;
SHIFT_LEFT(column 0 of T^1) = 1*(column 3 of T);
SHIFT_LEFT(column 0 of T^2) = 2*(column 4 of T);
where SHIFT_LEFT of column sequence shifts 1 place left.
Triangle T begins:
1;
1, 1;
4, 2, 1;
22, 8, 3, 1;
148, 44, 14, 4, 1;
1156, 296, 84, 22, 5, 1;
10192, 2312, 600, 148, 32, 6, 1;
99688, 20384, 4908, 1156, 242, 44, 7, 1;
1069168, 199376, 44952, 10192, 2084, 372, 58, 8, 1;
12468208, 2138336, 454344, 99688, 20012, 3528, 544, 74, 9, 1; ...
...
After initial term, column 1 is twice column 0.
Matrix inverse T^-1 = A111540 starts:
1;
-1, 1;
-2, -2, 1;
-8, -2, -3, 1;
-44, -8, -2, -4, 1;
-296, -44, -8, -2, -5, 1;
-2312, -296, -44, -8, -2, -6, 1;
-20384, -2312, -296, -44, -8, -2, -7, 1;
-199376, -20384, -2312, -296, -44, -8, -2, -8, 1; ...
where columns are all equal after initial terms;
compare columns of T^-1 to column 1 of T.
Matrix logarithm log(T) = A111541 is:
0;
1, 0;
3, 2, 0;
14, 5, 3, 0;
84, 22, 8, 4, 0;
600, 128, 36, 12, 5, 0;
4908, 896, 212, 58, 17, 6, 0;
44952, 7220, 1496, 360, 90, 23, 7, 0;
454344, 65336, 12128, 2652, 602, 134, 30, 8, 0;
5016768, 653720, 110288, 22320, 4736, 974, 192, 38, 9, 0; ...
compare column 0 of log(T) to column 2 of T.
		

Crossrefs

Cf. A111537 (column 1), A111538 (column 2), A111539 (row sums), A111540 (matrix inverse), A111541 (matrix log); related tables: A111528, A104980, A111544, A111553.

Programs

  • Mathematica
    T[n_, k_] := T[n, k] = If[nJean-François Alcover, Jan 24 2017, adapted from PARI *)
  • PARI
    T(n,k)=if(n
    				

Formula

T(n, k) = k*T(n, k+1) + Sum_{j=0..n-k-1} T(j+1, 1)*T(n, j+k+1) for n>k>0, with T(n, n) = 1, T(n+1, n) = n+1, T(n+2, 1) = 2*T(n+1, 0), T(n+3, 3) = T(n+1, 0), for n>=0.

A289428 Sum of factorial-Catalan numbers over a certain family of decorations.

Original entry on oeis.org

1, 3, 18, 144, 1368, 14688, 173664, 2226528, 30647808
Offset: 0

Views

Author

N. J. A. Sloane, Jul 06 2017

Keywords

Comments

The precise definition involves the use of certain symbols akin to the peace symbol.

Crossrefs

Formula

From Peter Bala, Dec 25 2019: (Start)
The following are conjectural (Cf. A145879):
Recurrence: a(n) = n*a(n-1) + 2*Sum_{k = 1..n} a(k-1)*a(n-k) with a(0) = 1.
O.g.f. as a regular C-fraction: 1/(1 - 3*x/(1 - 3*x/(1 - 4*x/(1 - 4*x/(1 - 5*x/(1 - 5*x/(1 - ... ))))))). Cf. A111537.
exp( Sum_{n >= 1} a(n)*(2*x)^n/n ) = 1 + 6*x + 54*x^2 + 636*x^3 + ... appears to have integer coefficients. (End)

A111540 Matrix inverse of triangle A111536.

Original entry on oeis.org

1, -1, 1, -2, -2, 1, -8, -2, -3, 1, -44, -8, -2, -4, 1, -296, -44, -8, -2, -5, 1, -2312, -296, -44, -8, -2, -6, 1, -20384, -2312, -296, -44, -8, -2, -7, 1, -199376, -20384, -2312, -296, -44, -8, -2, -8, 1, -2138336, -199376, -20384, -2312, -296, -44, -8, -2, -9, 1, -24936416, -2138336, -199376, -20384, -2312, -296
Offset: 0

Views

Author

Paul D. Hanna, Aug 06 2005

Keywords

Comments

The column sequences are derived from the logarithm of a factorial series (cf. A111537).

Examples

			Triangle begins:
1;
-1,1;
-2,-2,1;
-8,-2,-3,1;
-44,-8,-2,-4,1;
-296,-44,-8,-2,-5,1;
-2312,-296,-44,-8,-2,-6,1;
-20384,-2312,-296,-44,-8,-2,-7,1;
-199376,-20384,-2312,-296,-44,-8,-2,-8,1; ...
After initial terms, all columns are equal to -A111537.
		

Crossrefs

Programs

  • PARI
    T(n,k)=if(n
    				

Formula

T(n, n)=1 and T(n+1, n)=n+1, else T(n+k+1, k) = -A111537(k) for k>=1.

A200659 Triangle T(n,k), read by rows, given by (1,2,2,3,3,4,4,5,5,6,6,...) DELTA (1,0,1,0,1,0,1,0,1,0,1,0,1,...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 1, 1, 3, 4, 1, 13, 21, 9, 1, 71, 132, 76, 16, 1, 461, 955, 670, 200, 25, 1, 3447, 7782, 6309, 2374, 435, 36, 1, 29093, 70441, 63833, 28413, 6713, 833, 49, 1, 273343, 701352, 694500, 351512, 99868, 16240, 1456, 64, 1
Offset: 0

Views

Author

Philippe Deléham, Nov 20 2011

Keywords

Examples

			Triangle begins :
1
1, 1
3, 4, 1
13, 21, 9, 1
71, 132, 76, 16, 1
461, 955, 670, 200, 25, 1
3447, 7782, 6309, 2374, 435, 36, 1
29093, 70441, 63833, 28413, 6713, 833, 49, 1
273343, 701352, 694500, 351512, 99868, 16240, 1456, 64, 1
		

Crossrefs

Formula

Sum_{k, 0<=k<=n} T(n,k)*x^k = A153881(n+1), A000007(n), A003319(n), A111537(n), A111546(n), A111556(n), A177354(n-1) for x = -2,-1,0,1,2,3,4 respectively.
Sum_ {k, 0<=k<=n} T(n,k)*x^(n-k) = A000012(n), A111537(n), A167872(n) for x = 0,1,2 respectively.
T(k+1,k)=(k+1)^2.

A177354 a(n) is the moment of order n for the density measure 24*x^4*exp(-x)/( (x^4*exp(-x)*Ei(x) - x^3 - x^2 - 2*x - 6)^2 + Pi^2*x^8*exp(-2*x) ) over the interval 0..infinity.

Original entry on oeis.org

5, 35, 305, 3095, 35225, 439775, 5939225, 85961375, 1324702025, 21632195375, 372965377625, 6769644905375, 129049505347625, 2578419996023375, 53898389265685625, 1176832196718869375, 26798832693476455625, 635575680349115699375, 15677971277701873945625, 401729457433222058609375
Offset: 0

Views

Author

Groux Roland, Dec 10 2010

Keywords

Comments

Ei(.) is the exponential integral.
This is the case k=4 in the family a(n,k) = (1/k!)*( (n+k+2)!-(k+1)*(n+k+1)! -Sum_{i=0..n-1} (n+k-i)!*a(i,k) ). The values k = 0 to 3 are represented by A003319, A111537, A111546, and A111556.
a(n,k) is the moment of order n for the density k!*x^k*exp(-x)/((x^k*exp(-x)*Ei(x) - Pk(x))^2 + Pi^2*x^(2*k)*exp(-2*x)) on the interval 0..infinity with polynomials Pk(x) = Sum_{i=0..k-1} (k-1-i)!*x^i.

References

  • R. Groux, Polynômes orthogonaux et transformations intégrales, Cépadués, 2008, 125-129.

Programs

  • PARI
    a(n)=if(n==0, 5, (1/24)*( (n+6)! -5*(n+5)! -sum(i=0,n-1, (n+4-i)!*a(i) ) ) ); \\ Joerg Arndt, May 04 2013

Formula

a(n) = (1/24)*( (n+6)! - 5*(n+5)! - Sum_{i=0..n-1} (n+4-i)!*a(i) ).
a(n) = 5*A111532(n+1) (conjecture). - R. J. Mathar, Dec 14 2010
G.f.: 1/x/Q(0) - 1/x, where Q(k) = 1 - 3*x + k*x - x*(k+2)/Q(k+1); (continued fraction). - Sergei N. Gladkovskii, May 04 2013
G.f.: (1-x-2/G(0))/x^2, where G(k) = 1 + 1/(1 - x*(k+1)/(x*(k-1) + 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 05 2013
G.f.: 1/x^2 - 5/x - 2/(x^2*G(0)), where G(k) = 1 + 1/(1 - x*(k+5)/(x*(k+5) + 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 06 2013

A382218 Fixed points of A382217.

Original entry on oeis.org

1, 4, 5, 16, 17, 18, 19, 20, 21, 22, 23, 64, 65, 66, 67, 68, 69, 70, 71, 76, 77, 82, 83, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 304, 305, 306, 307, 308
Offset: 1

Views

Author

Rémy Sigrist, Mar 19 2025

Keywords

Comments

This sequence corresponds to positive integers with factorial base expansion (d_1, ..., d_w) (where d_1 > 0) such that for any i in 2..w, there is some j in 1..i-1 such that d_j > i-j.
Empirically, there are A111537(w+1) terms with w factorial base digits.

Examples

			A382217(5) = 5, so the number 5 belongs to this sequence.
A382217(6) = 1, so the number 6 does not belong to this sequence.
		

Crossrefs

Programs

  • PARI
    \\ See Links section.

A193603 Augmentation of the triangle A008949. See Comments.

Original entry on oeis.org

1, 1, 2, 1, 5, 8, 1, 9, 30, 44, 1, 14, 77, 212, 296, 1, 20, 163, 700, 1712, 2312, 1, 27, 305, 1877, 6882, 15476, 20384, 1, 35, 523, 4365, 22380, 73240, 154424, 199376, 1, 44, 840, 9134, 62479, 280630, 841312, 1683992, 2138336
Offset: 0

Views

Author

Clark Kimberling, Jul 31 2011

Keywords

Comments

For an introduction to the unary operation "augmentation" as applied to triangular arrays or sequences of polynomials, see A193091. The right edge of the triangle A193603 is A111537.

Examples

			First five rows of A193603:
1
1...2
1...5....8
1...9...30....44
1...14...77..212...296
		

Crossrefs

Programs

  • Mathematica
    p[n_, k_] := Sum[Binomial[n, h], {h, 0, k}] (* A008949 *)
    Table[p[n, k], {n, 0, 5}, {k, 0, n}]
    m[n_] := Table[If[i <= j, p[n + 1 - i, j - i], 0], {i, n}, {j, n + 1}]
    TableForm[m[4]]
    w[0, 0] = 1; w[1, 0] = p[1, 0]; w[1, 1] = p[1, 1];
    v[0] = w[0, 0]; v[1] = {w[1, 0], w[1, 1]};
    v[n_] := v[n - 1].m[n]
    TableForm[Table[v[n], {n, 0, 6}]] (* A193603 *)
    Flatten[Table[v[n], {n, 0, 8}]]
Showing 1-7 of 7 results.