A245651 Decimal expansion of eta/xi = A086318/A086317, a coefficient associated with the asymptotics of the number of weakly binary trees.

3, 1, 8, 7, 7, 6, 6, 2, 5, 9, 2, 5, 0, 2, 9, 6, 7, 5, 4, 8, 0, 0, 8, 1, 7, 6, 9, 7, 7, 8, 0, 1, 3, 1, 8, 1, 9, 7, 2, 1, 2, 4, 1, 8, 6, 7, 8, 7, 8, 7, 0, 1, 7, 0, 1, 9, 7, 5, 4, 9, 6, 8, 1, 7, 8, 9, 5, 7, 3, 2, 3, 4, 2, 6, 0, 2, 2, 9, 9, 0, 0, 6, 4, 0, 9, 1

Offset

0,1

References

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.6 Otter's Tree Enumeration Constants, p. 297.

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Nils Berglund, Christian Kuehn, Model Spaces of Regularity Structures for Space-Fractional SPDEs, Journal of Statistical Physics, Springer Verlag, 2017, 168 (2), pp.331-368; HAL Id : hal-01432157.

Eric Weisstein's MathWorld, Weakly binary tree

Example

0.31877662592502967548008176977801318197212418678787017019754968178957323426...

Mathematica

digits = 103; Clear[c, k]; c[0] = 2; c[n_] := c[n] = c[n-1]^2 + 2; k[n_] := k[n] = (Sqrt[c[n]^2^(-n)]*Sqrt[3 + Sum[1/Product[c[j], {j, 1, k}], {k, 1, n}]])/(c[n]^2^(-n)*(2*Sqrt[Pi])); k[5]; k[n = 10]; While[RealDigits[k[n], 10, digits] != RealDigits[k[n-5], 10, digits], n = n+5]; RealDigits[k[n], 10, digits] // First

Crossrefs

Cf. A086317, A086318.

Sequence in context: A270861 A208656 A242440 * A007023 A176103 A308666

Adjacent sequences: A245648 A245649 A245650 * A245652 A245653 A245654

Keyword

nonn,cons

Author

Jean-François Alcover, Jul 28 2014

Status

approved