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.

A018893 Blasius sequence: from coefficients in expansion of solution to Blasius's equation in boundary layer theory.

Original entry on oeis.org

1, 1, 11, 375, 27897, 3817137, 865874115, 303083960103, 155172279680289, 111431990979621729, 108511603921116483579, 139360142400556127213655, 230624017175131841824732233, 482197541715276031774659298833
Offset: 0

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Author

Stan Richardson (stan(AT)maths.ed.ac.uk)

Keywords

Comments

Number of increasing trilabeled unordered trees. - Markus Kuba, Nov 18 2014

Examples

			A(x) = 1 + 1/6*x^3 + 11/720*x^6 + 25/24192*x^9 + 9299/159667200*x^12 + ...
G.f. = 1 + x + 11*x^3 + 375*x^4 + 27897*x^5 + 3817137*x^6 + ...
		

References

  • H. T. Davis: Introduction to Nonlinear Differential and Integral Equations (Dover 1962), page 403.

Crossrefs

Programs

  • Mathematica
    a[0] = 1; a[k_] := a[k] = Sum[Binomial[3*k-1, 3*j]*a[j]*a[k-j-1], {j, 0, k-1}]; Table[a[k], {k, 0, 13}] (* Jean-François Alcover, Oct 28 2014 *)

Formula

E.g.f. A(x) satisfies (d^3/dx^3)log(A(x)) = A(x). - Vladeta Jovovic, Oct 24 2003
Lim_{n->infinity} (a(n)/(3*n+2)!)^(1/n) = 0.03269425181024... . - Vaclav Kotesovec, Oct 28 2014
T(z) = log(A(z)) satisfies T'''(z)=exp(T(z)), such that F(z)=T'(z) satisfies a Blasius type equation: F'''(z)-F(z)*F''(z)=0. - Markus Kuba, Nov 18 2014
a(n) = Sum_{v = 0..n-1} binomial(3*n-1, 3*v) * a(v) * a(n-1-v) for n >= 1 with a(0) = 1 (Blasius' recurrence). - Petros Hadjicostas, Aug 01 2019

Extensions

Corrected and extended by Vladeta Jovovic, Oct 24 2003