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 1-6 of 6 results.

A143508 G.f. A(x) satisfies A(x) = 1 + x*A(x*A(x)^2)^2.

Original entry on oeis.org

1, 1, 2, 9, 52, 372, 3058, 28074, 282028, 3059328, 35497672, 437499541, 5696752234, 78036803430, 1120687989348, 16823652188164, 263345788211608, 4289062071449610, 72543038644585822, 1271980596430351862, 23085579883157411532, 433071407705851089244
Offset: 0

Views

Author

Paul D. Hanna, Aug 21 2008

Keywords

Examples

			G.f. A(x) = 1 + x + 2*x^2 + 9*x^3 + 52*x^4 + 372*x^5 + 3058*x^6 +...
A(x)^2 = 1 + 2*x + 5*x^2 + 22*x^3 + 126*x^4 + 884*x^5 + 7149*x^6 +...
A(x*A(x)^2) = 1 + x + 4*x^2 + 22*x^3 + 156*x^4 + 1285*x^5 + 11886*x^6 +...
A(x*A(x)^2)^2 = 1 + 2*x + 9*x^2 + 52*x^3 + 372*x^4 + 3058*x^5 +...
Define G(x) by G(x*A(x)^2) = x, then
G(x) = x - 2*x^2 + 3*x^3 - 12*x^4 + 17*x^5 - 198*x^6 - 345*x^7 +...
such that G(x) = x/(1 + A(x)^2*G(x))^2.
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x+x*O(x^n));for(i=0,n,A=1+x*subst(A^2,x,x*A^2));polcoeff(A,n)}
    
  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(2*n-2*j+k, j)/(2*n-2*j+k)*a(n-j, 2*j))); \\ Seiichi Manyama, Mar 01 2025

Formula

Given g.f. A(x), let G(x) be defined by G(x*A(x)^2) = x, then
(1) G(x) = x/(1 + A(x)^2*G(x))^2,
(2) A(G(x)) = 1 + A(x)^2*G(x).
From Seiichi Manyama, Mar 01 2025: (Start)
Let a(n,k) = [x^n] A(x)^k.
a(n,0) = 0^n; a(n,k) = k * Sum_{j=0..n} binomial(2*n-2*j+k,j)/(2*n-2*j+k) * a(n-j,2*j). (End)

A381570 G.f. A(x) satisfies A(x) = (1 + x*A(x*A(x)))^3.

Original entry on oeis.org

1, 3, 12, 82, 732, 7944, 99156, 1381464, 21065853, 346932822, 6112226961, 114383442888, 2261347164766, 47025363829497, 1025005545866361, 23349137897005296, 554467427766694440, 13696046757037152183, 351231525904387758222, 9335221780768641038952
Offset: 0

Views

Author

Seiichi Manyama, Feb 28 2025

Keywords

Crossrefs

Column k=1 of A381569.

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(3*n-3*j+3*k, j)/(n-j+k)*a(n-j, j)));

Formula

See A381569.
G.f.: B(x)^3, where B(x) is the g.f. of A212029.

A381615 G.f. A(x) satisfies A(x) = 1/(1 - x * A(x*A(x)^3)^3).

Original entry on oeis.org

1, 1, 4, 31, 320, 3969, 56080, 876204, 14860614, 270231265, 5223002719, 106613106181, 2287120272173, 51367948203527, 1204141944566399, 29385603693050274, 744943334951904519, 19580887642660810193, 532781828387893449124, 14984377196395037979472
Offset: 0

Views

Author

Seiichi Manyama, Mar 01 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(3*n-2*j+k, j)/(3*n-2*j+k)*a(n-j, 3*j)));

Formula

Let a(n,k) = [x^n] A(x)^k.
a(n,0) = 0^n; a(n,k) = k * Sum_{j=0..n} binomial(3*n-2*j+k,j)/(3*n-2*j+k) * a(n-j,3*j).

A212028 G.f. satisfies: A(x) = 1 + x*A(x*A(x)^3)^2.

Original entry on oeis.org

1, 1, 2, 11, 74, 635, 6296, 70268, 864106, 11546531, 165996792, 2548556963, 41546769324, 715850868468, 12986529841038, 247255748839532, 4926870211273246, 102495266879754087, 2221254395951869988, 50049980203162990978, 1170440788530570387644
Offset: 0

Views

Author

Paul D. Hanna, Apr 27 2012

Keywords

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 11*x^3 + 74*x^4 + 635*x^5 + 6296*x^6 +...
Related expansions:
A(x)^2 = 1 + 2*x + 5*x^2 + 26*x^3 + 174*x^4 + 1462*x^5 + 14279*x^6 +...
A(x)^3 = 1 + 3*x + 9*x^2 + 46*x^3 + 306*x^4 + 2526*x^5 + 24311*x^6 +...
A(x*A(x)^3) = 1 + x + 5*x^2 + 32*x^3 + 273*x^4 + 2715*x^5 + 30542*x^6 + 379200*x^7 + 5117211*x^8 + 74266646*x^9 + 1150267802*x^10 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A^3, x, x*A^3)); polcoeff(A, n)}
    for(n=0,30,print1(a(n),", "))

A381649 G.f. A(x) satisfies A(x) = 1 + x * A(x)^2 * A(x*A(x)^3)^3.

Original entry on oeis.org

1, 1, 5, 44, 510, 7024, 109362, 1871530, 34590180, 682396379, 14251399805, 313170119013, 7207845252630, 173129413258492, 4327373963163746, 112289379643018983, 3018922654575996866, 83951253980821314446, 2411137697712963195801, 71427857356498491780290
Offset: 0

Views

Author

Seiichi Manyama, Mar 03 2025

Keywords

Crossrefs

Column k=1 of A381648.

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(3*n-j+k, j)/(3*n-j+k)*a(n-j, 3*j)));

Formula

See A381648.

A212030 G.f. satisfies: A(x) = 1 + x*A(x*A(x)^2)^3.

Original entry on oeis.org

1, 1, 3, 18, 142, 1350, 14607, 174626, 2263749, 31426878, 463144150, 7199095692, 117452998632, 2003613768328, 35628141598164, 658723330672311, 12636278430184303, 251042922016657782, 5156985005918404047, 109382326645948764003, 2392477607054828471286
Offset: 0

Views

Author

Paul D. Hanna, Apr 27 2012

Keywords

Examples

			G.f.: A(x) = 1 + x + 3*x^2 + 18*x^3 + 142*x^4 + 1350*x^5 + 14607*x^6 +...
Related expansions:
A(x)^2 = 1 + 2*x + 7*x^2 + 42*x^3 + 329*x^4 + 3092*x^5 + 33090*x^6 +...
A(x)^3 = 1 + 3*x + 12*x^2 + 73*x^3 + 570*x^4 + 5307*x^5 + 56226*x^6 +...
A(x*A(x)^2) = 1 + x + 5*x^2 + 37*x^3 + 346*x^4 + 3745*x^5 + 45132*x^6 +...
A(x*A(x)^2)^3 = 1 + 3*x + 18*x^2 + 142*x^3 + 1350*x^4 + 14607*x^5 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A^3, x, x*A^2)); polcoeff(A, n)}
    for(n=0,30,print1(a(n),", "))
Showing 1-6 of 6 results.