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 1-9 of 9 results.

A090362 G.f. satisfies A^6 = BINOMIAL(A)^5 and also equals A090358^5.

Original entry on oeis.org

1, 5, 40, 460, 7220, 148276, 3831760, 120333680, 4460572870, 190679906990, 9230084185456, 498734395394840, 29740372199558420, 1939241402832412180, 137222625361036807760, 10470376552560151801616, 856818090423771231257245
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

See comments in A090358.

Crossrefs

Programs

  • Mathematica
    nmax = 16; sol = {a[0] -> 1};
    Do[A[x_] = Sum[a[k] x^k, {k, 0, n}] /. sol; eq = CoefficientList[A[x]^6 - A[x/(1 - x)]^5/(1 - x)^5 + O[x]^(n + 1), x] == 0 /. sol; sol = sol ~Join~ Solve[eq][[1]], {n, 1, nmax}];
    sol /. Rule -> Set;
    a /@ Range[0, nmax] (* Jean-François Alcover, Nov 02 2019 *)
  • PARI
    {a(n)=local(A); if(n<0,0,A=1+x+x*O(x^n); for(k=1,n,B=subst(A,x,x/(1-x))/(1-x)+x*O(x^n); A=A-A^6+B^5);polcoeff(A,n,x))}

Formula

G.f.: A(x)^6 = A(x/(1-x))^5/(1-x)^5.
a(n) ~ (n-1)! / (6 * (log(6/5))^(n+1)). - Vaclav Kotesovec, Nov 19 2014
From Peter Bala, May 26 2015: (Start)
O.g.f.: A(x) = exp( Sum_{n >= 1} b(n)*x^n/n ), where b(n) = Sum_{k = 1..n} k!*Stirling2(n,k)*5^k = A094418(n).
BINOMIAL(A(x)) = exp( Sum_{n >= 1} c(n)*x^n/n ) where c(n) = (-1)^n*Sum_{k = 1..n} k!*Stirling2(n,k)*(-6)^k. A(x) = B(x)^5 and BINOMIAL(A(x)) = B(x)^6 where B(x) = 1 + x + 6*x^2 + 66*x^3 + 1071*x^4 + ... is the o.g.f. for A090358. See also A019538. (End)
G.f.: Product_{k>=1} 1/(1 - k*x)^((1/6) * (5/6)^k). - Seiichi Manyama, May 26 2025

A090359 Self-convolution equals the binomial transform of A090358: A^2 = BINOMIAL(A090358), where A090358^6 = BINOMIAL(A090358^5).

Original entry on oeis.org

1, 1, 4, 40, 640, 13816, 374636, 12229364, 466769330, 20391705290, 1003264704212, 54885373562372, 3304609250020008, 217139910688424400, 15461303963210314980, 1185856988993966140380, 97466557932008735970465
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

See comments in A090358.

Crossrefs

Cf. A090358.

Programs

  • PARI
    {a(n)=local(A); if(n<1,0,A=1+x+x*O(x^n); for(k=1,n,B=subst(A^5,x,x/(1-x))/(1-x)+x*O(x^n); A=A-A^6+B);B=subst(A,x,x/(1-x))/(1-x)+x*O(x^n); polcoeff(B^(1/2),n,x))}

Formula

a(n) ~ (n-1)! / (50 * (log(6/5))^(n+1)). - Vaclav Kotesovec, Nov 19 2014

A090360 Satisfies A^3 = BINOMIAL(A090358^2), where A090358^6 = BINOMIAL(A090358^5).

Original entry on oeis.org

1, 1, 5, 53, 855, 18471, 500651, 16334075, 623157898, 27214793210, 1338641476882, 73220527990322, 4408033139790830, 289619155572769806, 20620846574162157750, 1581511116725744872022, 129981009079318502310677
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

See comments in A090358.

Crossrefs

Cf. A090358.

Programs

  • PARI
    {a(n)=local(A); if(n<1,0,A=1+x+x*O(x^n); for(k=1,n,B=subst(A^5,x,x/(1-x))/(1-x)+x*O(x^n); A=A-A^6+B);B=subst(A^2,x,x/(1-x))/(1-x)+x*O(x^n); polcoeff(B^(1/3),n,x))}

Formula

a(n) ~ (n-1)! / (75/2 * (log(6/5))^(n+1)). - Vaclav Kotesovec, Nov 19 2014

A090361 Satisfies A^2 = BINOMIAL(A090358^3), where A090358^6 = BINOMIAL(A090358^5).

Original entry on oeis.org

1, 2, 12, 130, 2075, 44196, 1183492, 38254712, 1449394470, 62974889140, 3085705347128, 168283580164356, 10107641429213386, 662869582493716400, 47124829795282593000, 3609674673146922124600, 296355186635275737517175
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

See comments in A090358.

Crossrefs

Cf. A090358.

Programs

  • PARI
    {a(n)=local(A); if(n<1,0,A=1+x+x*O(x^n); for(k=1,n,B=subst(A^5,x,x/(1-x))/(1-x)+x*O(x^n); A=A-A^6+B);B=subst(A^3,x,x/(1-x))/(1-x)+x*O(x^n); polcoeff(B^(1/2),n,x))}

Formula

a(n) ~ (n-1)! / (50/3 * (log(6/5))^(n+1)). - Vaclav Kotesovec, Nov 19 2014

A090351 G.f. satisfies A^3 = BINOMIAL(A^2).

Original entry on oeis.org

1, 1, 3, 15, 108, 1032, 12388, 179572, 3052986, 59555338, 1310677726, 32114051862, 866766965308, 25547102523604, 816335926158372, 28107705687291892, 1037367351120788551, 40852168787823027351, 1709792654612819858341
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

In general, if A^n = BINOMIAL(A^(n-1)), then for all integer m>0 there exists an integer sequence B such that B^d = BINOMIAL(A^m) where d=gcd(m+1,n). Also, coefficients of A(k*x)^n = k-th binomial transform of coefficients in A(k*x)^(n-1) for all k>0.

Examples

			A^3 = BINOMIAL(A090352), since A090352=A^2.
		

Crossrefs

Programs

  • Magma
    m:=40;
    f:= func< n,x | Exp((&+[(&+[2^(j-1)*Factorial(j)* StirlingSecond(k,j)*x^k/k: j in [1..k]]): k in [1..n+2]])) >;
    R:=PowerSeriesRing(Rationals(), m+1);  // A090351
    Coefficients(R!( f(m,x) )); // G. C. Greubel, Jun 08 2023
    
  • Mathematica
    nmax = 18; sol = {a[0] -> 1};
    Do[A[x_] = Sum[a[k] x^k, {k, 0, n}] /. sol; eq = CoefficientList[A[x]^3 - A[x/(1 - x)]^2/(1 - x) + O[x]^(n + 1), x] == 0 /. sol; sol = sol ~Join~ Solve[eq][[1]], {n, 1, nmax}];
    sol /. Rule -> Set;
    a /@ Range[0, nmax] (* Jean-François Alcover, Nov 02 2019 *)
    With[{m=40}, CoefficientList[Series[Exp[Sum[Sum[2^(j-1)*j!* StirlingS2[k,j], {j,k}]*x^k/k, {k,m+1}]], {x,0,m}], x]] (* G. C. Greubel, Jun 08 2023 *)
  • PARI
    {a(n) = my(A); if(n<0,0,A = 1+x +x*O(x^n); for(k=1,n, B = subst(A^2,x,x/(1-x))/(1-x) +x*O(x^n); A = A - A^3 + B); polcoef(A,n,x))}
    for(n=0,25,print1(a(n),", "))
    
  • SageMath
    m=50
    def f(n, x): return exp(sum(sum(2^(j-1)*factorial(j)* stirling_number2(k,j)*x^k/k for j in range(1,k+1)) for k in range(1,n+2)))
    def A090351_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(m,x) ).list()
    A090351_list(m-9) # G. C. Greubel, Jun 08 2023

Formula

G.f. satisfies: A(x)^3 = A(x/(1-x))^2 / (1-x).
a(n) ~ (n-1)! / (6 * (log(3/2))^(n+1)). - Vaclav Kotesovec, Nov 18 2014
O.g.f. A(x) = exp( Sum_{n >= 1} b(n)*x^n/n ), where b(n) = Sum_{k = 1..n} k!*Stirling2(n,k)*2^(k-1) = A050351(n) = 1/2*A004123(n+1) for n >= 1. - Peter Bala, May 26 2015
G.f. satisfies [x^n] 1/A(x)^(2*n-2) = [x^n] 1/A(x)^(3*n-3) = -(n-1)*A088222(n) for n >= 0. - Paul D. Hanna, Apr 28 2025
G.f.: Product_{k>=1} 1/(1 - k*x)^((1/6) * (2/3)^k). - Seiichi Manyama, May 26 2025

A090353 G.f. satisfies A^4 = BINOMIAL(A^3).

Original entry on oeis.org

1, 1, 4, 28, 286, 3886, 66260, 1361972, 32784353, 904412593, 28124223808, 973106096392, 37073604836768, 1541948625066176, 69513081435903392, 3376138396206853792, 175739519606046355540, 9760024269508314079444
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

In general, if A^n = BINOMIAL(A^(n-1)), then for all integer m>0 there exists an integer sequence B such that B^d = BINOMIAL(A^m) where d=gcd(m+1,n). Also, coefficients of A(k*x)^n = k-th binomial transform of coefficients in A(k*x)^(n-1) for all k>0.

Examples

			A^4 = BINOMIAL(A090355), since A090355=A^3. Also, BINOMIAL(A) = A090354^2.
		

Crossrefs

Programs

  • Magma
    m:=40;
    f:= func< n,x | Exp((&+[(&+[3^(j-1)*Factorial(j)* StirlingSecond(k,j)*x^k/k: j in [1..k]]): k in [1..n+2]])) >;
    R:=PowerSeriesRing(Rationals(), m+1); // A090353
    Coefficients(R!( f(m,x) )); // G. C. Greubel, Jun 09 2023
    
  • Mathematica
    nmax = 17; sol = {a[0] -> 1};
    Do[A[x_] = Sum[a[k] x^k, {k, 0, n}] /. sol; eq = CoefficientList[A[x]^4 - A[x/(1 - x)]^3/(1 - x) + O[x]^(n + 1), x] == 0 /. sol; sol = sol ~Join~ Solve[eq][[1]], {n, 1, nmax}];
    sol /. Rule -> Set;
    a /@ Range[0, nmax] (* Jean-François Alcover, Nov 02 2019 *)
    With[{m=40}, CoefficientList[Series[Exp[Sum[Sum[3^(j-1)*j!* StirlingS2[k,j], {j,k}]*x^k/k, {k,m+1}]], {x,0,m}], x]] (* G. C. Greubel, Jun 09 2023 *)
  • PARI
    {a(n) = my(A); if(n<0,0,A=1+x +x*O(x^n); for(k=1,n, B = subst(A^3,x,x/(1-x))/(1-x)+x*O(x^n); A = A - A^4 + B); polcoef(A,n,x))}
    for(n=0,20,print1(a(n),", "))
    
  • SageMath
    m=50
    def f(n, x): return exp(sum(sum(3^(j-1)*factorial(j)* stirling_number2(k,j)*x^k/k for j in range(1,k+1)) for k in range(1,n+2)))
    def A090353_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(m,x) ).list()
    A090353_list(m-9) # G. C. Greubel, Jun 09 2023

Formula

G.f. satisfies: A(x)^4 = A(x/(1-x))^3/(1-x).
a(n) ~ (n-1)! / (12 * (log(4/3))^(n+1)). - Vaclav Kotesovec, Nov 19 2014
O.g.f.: A(x) = exp( Sum_{n >= 1} b(n)*x^n/n ), where b(n) = Sum_{k = 1..n} k!*Stirling2(n,k)*3^(k-1) = A050352(n) = 1/3*A032033(n) for n >= 1. - Peter Bala, May 26 2015
G.f. satisfies [x^n] 1/A(x)^(3*n-3) = [x^n] 1/A(x)^(4*n-4) for n >= 0. - Paul D. Hanna, Apr 28 2025
G.f.: Product_{k>=1} 1/(1 - k*x)^((1/12) * (3/4)^k). - Seiichi Manyama, May 26 2025

A090356 G.f. A(x) satisfies A(x)^5 = BINOMIAL(A(x)^4); that is, the binomial transform of the coefficients in A(x)^4 yields the coefficients in A(x)^5.

Original entry on oeis.org

1, 1, 5, 45, 595, 10475, 231255, 6148495, 191276600, 6815243040, 273601200136, 12217471594856, 600580173151560, 32224787998758280, 1873909224391774760, 117388347849375956328, 7880739469498103077588, 564440024187816634143380
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2003

Keywords

Comments

In general, if A^n = BINOMIAL(A^(n-1)), then for all integer m>0 there exists an integer sequence B such that B^d = BINOMIAL(A^m) where d=gcd(m+1,n). Also, coefficients of A(k*x)^n = k-th binomial transform of coefficients in A(k*x)^(n-1) for all k>0.

Examples

			G.f.: A(x) = 1 + x + 5*x^2 + 45*x^3 + 595*x^4 + 10475*x^5 + 231255*x^6 + ...
The coefficients in A(x)^4 are given by A090357 and begin
A(x)^4: [1, 4, 26, 244, 3131, 52600, 1111940, ..., A090357(n), ...].
The binomial transform of A090357 yields the coefficients of A(x)^5:
A(x)^5: [1, 5, 35, 335, 4280, 70976, 1479800, ...]
as shown by
1 = 1*1,
5 = 1*1 + 1*4,
35 = 1*1 + 2*4 + 1*26,
335 = 1*1 + 3*4 + 3*26 + 1*244,
4280 = 1*1 + 4*4 + 6*26 + 4*244 + 1*3131, ...
		

Crossrefs

Programs

  • Magma
    m:=40;
    f:= func< n,x | Exp((&+[(&+[4^(j-1)*Factorial(j)* StirlingSecond(k,j)*x^k/k: j in [1..k]]): k in [1..n+2]])) >;
    R:=PowerSeriesRing(Rationals(), m+1); // A090356
    Coefficients(R!( f(m,x) )); // G. C. Greubel, Jun 09 2023
    
  • Mathematica
    nmax = 17; sol = {a[0] -> 1};
    Do[A[x_] = Sum[a[k] x^k, {k, 0, n}] /. sol; eq = CoefficientList[A[x]^5 - A[x/(1 - x)]^4/(1 - x) + O[x]^(n + 1), x] == 0 /. sol; sol = sol ~Join~ Solve[eq][[1]], {n, 1, nmax}];
    sol /. Rule -> Set;
    a /@ Range[0, nmax] (* Jean-François Alcover, Nov 02 2019 *)
    With[{m = 40}, CoefficientList[Series[Exp[Sum[Sum[4^(j-1)*j!* StirlingS2[k,j], {j,k}]*x^k/k, {k,m+1}]], {x,0,m}], x]] (* G. C. Greubel, Jun 09 2023 *)
  • PARI
    {a(n)=local(A); if(n<1,0,A=1+x+x*O(x^n); for(k=1,n,B=subst(A^4,x,x/(1-x))/(1-x)+x*O(x^n); A=A-A^5+B);polcoeff(A,n,x))}
    
  • SageMath
    m=40
    def f(n, x): return exp(sum(sum(4^(j-1)*factorial(j)* stirling_number2(k,j)*x^k/k for j in range(1,k+1)) for k in range(1,n+2)))
    def A090356_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(m,x) ).list()
    A090356_list(m) # G. C. Greubel, Jun 09 2023

Formula

G.f. satisfies: A(x)^5 = A(x/(1-x))^4/(1-x).
a(n) ~ (n-1)! / (20 * (log(5/4))^(n+1)). - Vaclav Kotesovec, Nov 19 2014
O.g.f.: A(x) = exp( Sum_{n >= 1} b(n)*x^n/n ), where b(n) = Sum_{k = 1..n} k!*Stirling2(n,k)*4^(k-1) = A050353(n) = 1/4*A094417(n) for n >= 1. - Peter Bala, May 26 2015
G.f.: Product_{k>=1} 1/(1 - k*x)^((1/20) * (4/5)^k). - Seiichi Manyama, May 26 2025

A258377 O.g.f. satisfies A^2(z) = 1/(1 - z)*( BINOMIAL(BINOMIAL(A(z))) ).

Original entry on oeis.org

1, 3, 13, 79, 649, 6955, 93813, 1539991, 29884881, 669628819, 17005862301, 482399018527, 15108642099673, 517599894435643, 19247498583665029, 771922934908235751, 33206411983713679009, 1525025984109289947171, 74466779211331635306029, 3852255519421356879419631
Offset: 0

Views

Author

Peter Bala, May 28 2015

Keywords

Comments

For a fixed integer N, Hanna has considered the problem of finding an o.g.f. of the form A(z) = 1 + N*z + a(2)*z^2 + a(3)*z^3 + ..., with integer coefficients a(2), a(3), ... dependent on the parameter N, which is a solution to the functional equation A^(N+1) = ( BINOMIAL(A) )^N. Here BINOMIAL(F(z))= 1/(1 - z)*F(z/(1 - z)) denotes the binomial transform of the o.g.f. F(z).
The function A(z) is related to the triangle of ordered Stirling numbers A019538 via logarithmic differentiation. It can be shown that z*A'(z)/A(z) = Sum_{k >= 1} R(k,N)*z^k, where R(k,x) denotes the k-th row polynomial of A019538; equivalently, A(z) = exp( Sum_{k >= 1} R(k,N)*z^k/k ).
Cases include A084784 (N = 1), A090352 (N = 2), A090355 (N = 3), A090357 (N = 4), A090362 (N = 5) and a signed version of A084785 (N = -2).
It turns out that the o.g.f. B(z) := A(z)^(1/N) also has integer coefficients. It satisfies the functional equation B^(N+1) = BINOMIAL(B^N). For cases see A084784 (N = 1), A090351 (N = 2), A090353 (N = 3), A090356 (N = 4), A090358 (N = 5) and A084784 (N = -2).
There are similar results to the above associated with triangle A145901, which can be viewed as a type B analog of A019538.
For a fixed integer N, consider the problem of finding an o.g.f. with integer coefficients (depending on the parameter N) of the form A(z) = 1 + N*z + a(2)*z^2 + a(3)*z^3 + ..., which is a solution to the functional equation A^(N+1)(z) = 1/(1 - z) * ( BINOMIAL(BINOMIAL(A(z))) )^N; equivalently A^(N+1)(z) = 1/(1 - z)* 1/(1 - 2*z)^N*A^N(z/(1 - 2*z)). This is the type B analog of Hanna's type A functional equation above.
It can be shown that z*A'(z)/A(z) = Sum_{k >= 1} P(k,N)*z^k, where P(k,x) denotes the k-th row polynomial of A145901. However, unlike the type A situation, the type B function A(z)^(1/N) does not have all integer coefficients.
The present sequence is the case N = 1. For further examples of solutions to the type B functional equation see A258378 (N = 2), A258379 (N = 3), A258380 (N = 4) and A258381 (N = 5).
From Peter Bala, Dec 06 2017: (Start)
a(n) appears to be always odd. Calculation suggests that for k = 1,2,3,..., the sequence a(n) (mod 2^k) is purely periodic with period 2^(k-1). For example, a(n) (mod 4) = (1,3,1,3,...) seems to be purely periodic with period 2 and a(n) (mod 8) = (1,3,5,7,1,3,5,7,...) seems to be purely periodic with period 4 (both checked up to n = 1000).
(End)

Crossrefs

Programs

  • Maple
    #A258377
    with(combinat):
    #recursively define row polynomials R(n,x) of A145901
    R := proc (n, x) option remember; if n = 0 then 1 else 1 + x*add(binomial(n, i)*2^(n-i)*R(i,x), i = 0..n-1) end if; end proc:
    #define a family of sequences depending on an integer parameter k
    a := proc (n, k) option remember; if n = 0 then 1 else 1/n*add(R(i+1,k)*a(n-1-i,k), i = 0..n-1) end if; end proc:
    # display the case k = 1
    seq(a(n,1), n = 0..19);
  • Mathematica
    R[n_, x_] := R[n, x] = If[n==0, 1, 1+x*Sum[Binomial[n, i]*2^(n-i)*R[i, x], {i, 0, n-1}]];
    a[n_, k_] := a[n, k] = If[n==0, 1, 1/n*Sum[R[i+1, k]*a[n-1-i, k], {i, 0, n-1}]];
    a[n_] := a[n, 1];
    a /@ Range[0, 19] (* Jean-François Alcover, Oct 02 2019 *)

Formula

a(0) = 1 and for n >= 1, a(n) = 1/n*Sum_{i = 0..n-1} R(i+1,1)*a(n-1-i), where R(n,x) denotes the n-th row polynomial of A145901.
O.g.f.: A(z) = 1 + 3*z + 13*z^2 + 79*z^3 + 649*z^4 + ... satisfies A^2(z) = 1/(1 - z)*1/(1 - 2*z)*A(z/(1 - 2*z)).
O.g.f.: A(z) = exp( Sum_{k >= 1} R(k,1)*z^k/k ).
1 + z*A'(z)/A(z) = 1 + 3*z + 17*z^2 + 147*z^3 + 1697*z^4 + ... is the o.g.f. for A080253.
a(n) = Sum_{j=0..n} binomial(n,j) * A084783(n,n-j). - Alois P. Heinz, Jun 09 2023
a(n) ~ (n-1)! * 2^(n - 1/2) / log(2)^(n+1). - Vaclav Kotesovec, May 28 2025

A384305 Expansion of Product_{k>=1} 1/(1 - k*x)^((5/6)^k).

Original entry on oeis.org

1, 30, 615, 11260, 205695, 4013406, 88035585, 2255192280, 68859250020, 2506898720040, 107238427737876, 5281094776037040, 293625956135692020, 18139856902224931080, 1229886945212115522060, 90641666662687182976896, 7206758883035555464430370, 614391718014749017022916060
Offset: 0

Views

Author

Seiichi Manyama, May 26 2025

Keywords

Crossrefs

Programs

  • Mathematica
    terms = 20; A[] = 1; Do[A[x] = -5*A[x] + 6*A[x/(1-x)]^(5/6) / (1-x)^5 + O[x]^j // Normal, {j, 1, terms}]; CoefficientList[A[x], x] (* Vaclav Kotesovec, May 31 2025 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(exp(6*sum(k=1, N, sum(j=0, k, 5^j*j!*stirling(k, j, 2))*x^k/k)))

Formula

G.f. A(x) satisfies A(x) = A(x/(1-x))^(5/6) / (1-x)^5.
G.f.: exp(6 * Sum_{k>=1} A094418(k) * x^k/k).
G.f.: B(x)^30, where B(x) is the g.f. of A090358.
a(n) ~ (n-1)! / log(6/5)^(n+1). - Vaclav Kotesovec, May 31 2025
Showing 1-9 of 9 results.