A067609 Number of stereo alkanes with combinatorial diameter n.

1, 1, 3, 6, 58, 861, 373141, 525901096, 92709102076260838, 65190291939775823483614581, 1416591403847441323962646602694082865630539057192433

Offset

1,3

References

R. Davies and P. J. Freyd, C_{167}H_{336} is The Smallest Alkane with More Realizable Isomers than the Observable Universe has Particles, Journal of Chemical Education, Vol. 66, April 1989, pp. 278-281.

Links

Table of n, a(n) for n=1..11.

Mathematica

f[n_, k_] := Binomial[n+k-1, k]+Binomial[n, k]; rid[0]=1; rid[r_] := rid[r]=1+f[rid[r-1], 3]; rd[r_] := rid[r]-rid[r-1]; td[1]=1; td[r_] := If[EvenQ[r], Binomial[rd[r/2]+1, 2], f[rid[(r-1)/2], 4]-rd[(r-1)/2]f[rid[(r-3)/2], 3]-f[rid[(r-3)/2], 4]]; td/@Range[12]

Crossrefs

Cf. A000602, A000628, A067608, A067610.

Sequence in context: A370520 A303351 A067610 * A012473 A058161 A012877

Adjacent sequences: A067606 A067607 A067608 * A067610 A067611 A067612

Keyword

nonn

Author

Peter Freyd (pjf(AT)saul.cis.upenn.edu), Feb 02 2002

Extensions

Edited by Dean Hickerson, Feb 11 2002

Status

approved