A298202 Number of Eulerian cycles in the n-Sierpinski sieve graph.

1, 16, 102400, 40823664148480000, 4024143600922674552523331296813921054228480000000000

Offset

1,2

Comments

a(6) has 157 decimal digits. - Andrew Howroyd, Sep 10 2019

Links

Andrew Howroyd, Table of n, a(n) for n = 1..7

Eric Weisstein's World of Mathematics, Eulerian Cycle

Eric Weisstein's World of Mathematics, Sierpinski Sieve Graph

Mathematica

NestList[Function[{e, f, g}, {16 e^3 + 48 f e^2, 3 e^3 + (32 f + 8 g) e^2 + 56 f^2 e, e^3 + (30 f + 12 g) e^2 + (156 f^2 + 96 g f) e + 112 f^3}] @@ # &, {1, 0, 0}, 5][[All, 1]] (* Eric W. Weisstein, Feb 02 2024 based on code from Andrew Howroyd *)

Prog

(PARI)
P(u)={my([e, f, g]=u); [16*e^3 + 48*f*e^2, 3*e^3 + (32*f + 8*g)*e^2 + 56*f^2*e, e^3 + (30*f + 12*g)*e^2 + (156*f^2 + 96*g*f)*e + 112*f^3]}
a(n)={my(u=[1, 0, 0]); for(n=2, n, u=P(u)); u[1]} \\ Andrew Howroyd, Sep 12 2019

Crossrefs

Cf. A246959.

Sequence in context: A308507 A144830 A278289 * A364777 A332090 A333863

Adjacent sequences: A298199 A298200 A298201 * A298203 A298204 A298205

Keyword

nonn

Author

Eric W. Weisstein, Jan 14 2018

Extensions

a(4)-a(5) from Andrew Howroyd, Sep 10 2019

Status

approved