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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A386449 G.f. A(x) satisfies A(x) = 1/(1 - x - x^4*A'''(x)).

Original entry on oeis.org

1, 1, 1, 1, 7, 181, 11215, 1368049, 290015209, 98023774645, 49599740115757, 35810914359761065, 35524377449180431975, 46963191178201310535625, 80682726920407341929523811, 176372394085267937467487988481, 481849299958664384125278899595601, 1619977170089211596368385150640702601
Offset: 0

Views

Author

Seiichi Manyama, Jul 22 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, sum(k=1, 3, stirling(3, k, 1)*j^k)*v[j+1]*v[i-j])); v;

Formula

a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (2*k - 3*k^2 + k^3) * a(k) * a(n-1-k).

A386450 G.f. A(x) satisfies A(x) = 1/(1 - x - x^5*A''''(x)).

Original entry on oeis.org

1, 1, 1, 1, 1, 25, 3049, 1103713, 929323297, 1563120681841, 4730002253928145, 23848669801185169825, 188929157434986723256801, 2244856224793842495701519113, 38526222340982767558002054899641, 925631015719595748793089592291450945, 30325523298479173582153602405524578371265
Offset: 0

Views

Author

Seiichi Manyama, Jul 22 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, sum(k=1, 4, stirling(4, k, 1)*j^k)*v[j+1]*v[i-j])); v;

Formula

a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (-6*k + 11*k^2 - 6*k^3 + k^4) * a(k) * a(n-1-k).

A386451 G.f. A(x) satisfies A(x) = 1/(1 - x - x^6*A'''''(x)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 121, 87361, 220324321, 1481019998401, 22395984195495601, 677299352559157967041, 37550830682188851813205921, 3568906049019293501471580099841, 551188987985086896272084982413188201, 132418744847944340085178947237195978556801, 47718683730343729293790168893699493431209021761
Offset: 0

Views

Author

Seiichi Manyama, Jul 22 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, sum(k=1, 5, stirling(5, k, 1)*j^k)*v[j+1]*v[i-j])); v;

Formula

a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (24*k - 50*k^2 + 35*k^3 - 10*k^4 + k^5) * a(k) * a(n-1-k).

A386453 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} binomial(k+2,3) * a(k) * a(n-1-k).

Original entry on oeis.org

1, 1, 2, 11, 131, 2888, 107027, 6212005, 534389458, 65203760863, 10889677250198, 2417582805875622, 696275799766601842, 254839529849806176727, 116462397939843834894367, 65452132793842930368844779, 44638474752168615525812508053, 36514339485766910607857620043816
Offset: 0

Views

Author

Seiichi Manyama, Jul 22 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, binomial(j+2, 3)*v[j+1]*v[i-j])); v;

Formula

G.f. A(x) satisfies A(x) = 1/( 1 - x - x*Sum_{k=1..3} binomial(2,k-1) * x^k/k! * (d^k/dx^k A(x)) ).

A386454 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} binomial(k+3,4) * a(k) * a(n-1-k).

Original entry on oeis.org

1, 1, 2, 13, 220, 8148, 586948, 75141039, 15930666825, 5289069956220, 2628685323745449, 1884772989271329869, 1890430039448133854031, 2584219798288871040676608, 4708450397910844142927823544, 11215531466814325127916787062534, 34341962107081618846057340207455738
Offset: 0

Views

Author

Seiichi Manyama, Jul 22 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, binomial(j+3, 4)*v[j+1]*v[i-j])); v;

Formula

G.f. A(x) satisfies A(x) = 1/( 1 - x - x*Sum_{k=1..4} binomial(3,k-1) * x^k/k! * (d^k/dx^k A(x)) ).

A386455 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} binomial(k+4,5) * a(k) * a(n-1-k).

Original entry on oeis.org

1, 1, 2, 15, 344, 19962, 2555592, 649147331, 301207446317, 239159429472132, 308276821981867349, 617786997525975886618, 1856450241316927094671750, 8112688179283378712969957414, 50217541700003149682333160103969, 430364340522944093019900101527085125
Offset: 0

Views

Author

Seiichi Manyama, Jul 22 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, binomial(j+4, 5)*v[j+1]*v[i-j])); v;

Formula

G.f. A(x) satisfies A(x) = 1/( 1 - x - x*Sum_{k=1..5} binomial(4,k-1) * x^k/k! * (d^k/dx^k A(x)) ).

A091063 Triangle, read by rows, such that the initial terms of the binomial transform of the n-th row forms the n-th row of triangle A059438 transposed (permutations of [1..n] with k components).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 5, 7, 0, 1, 4, 9, 18, 34, 0, 1, 5, 14, 34, 86, 206, 0, 1, 6, 20, 56, 162, 508, 1476, 0, 1, 7, 27, 85, 269, 939, 3549, 12123, 0, 1, 8, 35, 122, 415, 1540, 6413, 28498, 111866, 0, 1, 9, 44, 168, 609, 2361, 10314, 50382, 257922, 1143554, 0, 1
Offset: 0

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Author

Paul D. Hanna, Dec 17 2003

Keywords

Comments

The main diagonal equals A075834 shift 1 place left; subsequent diagonals of this triangle are self-convolutions of the main diagonal. A075834 has the property that the n-th term of the n-th self-convolution of A075834 equals n!. The first (n+1) terms of the binomial transform of the n-th row forms the n-th row of triangle A059438 transposed, which has row sums equal to the factorials. A059438 is also formed from the self-convolutions of its main diagonal (A003319).

Examples

			Rows begin:
{1},
{1,0},
{1,1,0},
{1,2,2,0},
{1,3,5,7,0},
{1,4,9,18,34,0},
{1,5,14,34,86,206,0},
{1,6,20,56,162,508,1476,0},
{1,7,27,85,269,939,3549,12123,0},...
Initial terms of the binomial transform of each row forms A059438:
{1},
{1,1},
{1,2,3},
{1,3,7,13},
{1,4,12,32,71},
{1,5,18,58,177,461},
{1,6,25,92,327,1142,3447},
{1,7,33,135,531,2109,8411,29093},
{1,8,42,188,800,3440,15366,69692,273343},...
which has row sums equal to the factorials.
		

Crossrefs

A136633 G.f.: A(x) = Series_Reversion( x / Sum_{n>=0} (n+1)!*x^n ).

Original entry on oeis.org

1, 2, 10, 68, 544, 4832, 46312, 471536, 5055328, 56795840, 667286656, 8197599104, 105446118784, 1423627264256, 20234885027968, 303737480337152, 4827671316780544, 81385455480335360, 1455806861755411456
Offset: 0

Views

Author

Paul D. Hanna, Jan 14 2008

Keywords

Examples

			G.f.: A(x) = 1 + 2*x + 10*x^2 + 68*x^3 + 544*x^4 + 4832*x^5 + 46312*x^6 +...
Let F(x) = 1 + 2x + 6x^2 + 24x^3 + 120x^4 + 720x^5 +...+ (n+1)!*x^n +...
then A(x) = F(x*A(x)) and A(x/F(x)) = F(x);
also, a(n) = coefficient of x^n in F(x)^n divided by (n+1).
The g.f. A(x) also satisfies:
A(x) = 1 + 2*x*A(x)/(1+x*A(x)) + 2*2^2*x^2*A(x)^2/(1+2*x*A(x))^2 + 2*3^3*x^3*A(x)^3/(1+3*x*A(x))^3 + 2*4^4*x^4*A(x)^4/(1+4*x*A(x))^4 +...
		

Crossrefs

Programs

  • PARI
    a(n)=polcoeff(serreverse(x/sum(k=0,n,(k+1)!*x^k +x*O(x^n))),n)
    
  • PARI
    a(n)=local(A=1+x); for(i=1, n, A=1+2*sum(m=1, n, m^m*x^m*A^m/(1+m*x*A+x*O(x^n))^m)); polcoeff(A, n)
    for(n=0, 30, print1(a(n), ", ")) \\ Paul D. Hanna, Feb 04 2013

Formula

G.f. A(x) satisfies:
(1) A(x) = F(x*A(x)) and A(x/F(x)) = F(x);
(2) a(n) = [x^n] F(x)^n / (n+1);
where F(x) = Sum_{n>=0} (n+1)!*x^n.
G.f. satisfies: A(x) = 1 + 2*Sum_{n>=1} n^n * x^n * A(x)^n / (1 + n*x*A(x))^n. - Paul D. Hanna, Feb 04 2013
a(n) ~ exp(2) * n! * n. - Vaclav Kotesovec, Nov 23 2024

A230253 Coefficients of power series A(x) such that coefficient of x^n in A(x)^(n+1) equals (n+1)*(n+2)!/2 for n>=0.

Original entry on oeis.org

1, 3, 3, 6, 27, 162, 1206, 10476, 103059, 1125738, 13473378, 174997908, 2448791838, 36706645908, 586646510796, 9957100024152, 178868488496643, 3390603439026618, 67639341903290730, 1416612563019545220, 31079692422132040170, 712855563504590236860, 17061654943814209044660
Offset: 0

Views

Author

Paul D. Hanna, Oct 13 2013

Keywords

Examples

			G.f. A(x) = 1 + 3*x + 3*x^2 + 6*x^3 + 27*x^4 + 162*x^5 + 1206*x^6 +...
The coefficients in A(x)^n begin:
n=1: [(1),3,   3,    6,    27,    162,   1206,   10476,   103059, ...];
n=2: [1, (6), 15,   30,    99,    522,   3582,   29484,   278883, ...];
n=3: [1,  9, (36),  99,   297,   1323,   8208,   63342,   572751, ...];
n=4: [1, 12,  66, (240),  783,   3132,  17298,  123552,  1060155, ...];
n=5: [1, 15, 105,  480, (1800),  7083,  35415,  231660,  1869885, ...];
n=6: [1, 18, 153,  846,  3672, (15120), 71415,  428490,  3226797, ...];
n=7: [1, 21, 210, 1365,  6804,  30240,(141120), 789939,  5529573, ...];
n=8: [1, 24, 276, 2064, 11682,  56736, 270720,(1451520), 9485343, ...];
n=9: [1, 27, 351, 2970, 18873, 100440, 500904, 2643840,(16329600), ...]; ...
where the coefficient of x^n in A(x)^(n+1) equals (n+1)*(n+2)!/2 for n>=0.
Notice that the diagonal above the main diagonal forms A111546.
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(x/serreverse(sum(m=1, n+1, (m+1)!/2*x^m)+x^2*O(x^n)), n)}

Formula

[x^n] A(x)^n = A111546(n) for n>=0.

A363431 Number of 123-avoiding stabilized-interval-free permutations of size n.

Original entry on oeis.org

1, 1, 1, 2, 5, 14, 44, 150, 496, 1758, 6018, 21782, 76414, 280448, 1001752, 3714032, 13450270, 50259604, 183995056, 691863078, 2555043320, 9657267848, 35921300392, 136360740016, 510267869416, 1944193285228, 7312488701868, 27950641500876, 105590010259396, 404724123141348, 1534775681029994
Offset: 0

Views

Author

Juan B. Gil, Jun 22 2023

Keywords

Comments

A stabilized-interval-free (SIF) permutation on [n] = {1, 2, ..., n} is one that does not stabilize any proper subinterval of [n].

Examples

			For n=4 the a(4)=5 permutations are 2413, 3142, 3412, 3421, 4312.
		

Crossrefs

Cf. A075834.

Formula

For n>2, a(n) = f_0(n) - f_1(n-1) + f_2(n) - Sum_{k=1..floor((n-3)/2)} C(k)^2*a(n-2*k), where C(k)=binomial(2*k,k)/(k+1) and f_j(m) denotes the number of 123-avoiding permutations of size m having j fixed points.
Previous Showing 21-30 of 36 results. Next