|
| |
|
|
A007649
|
|
Number of set-like molecular species of degree n.
(Formerly M0824)
|
|
1
| |
|
|
1, 1, 2, 3, 7, 9, 20, 26, 54, 74, 137, 184, 356, 473, 841, 1154, 2034, 2742, 4740, 6405, 10874, 14794, 24515, 33246, 54955, 74380, 120501, 163828, 263144, 356621, 567330, 768854, 1212354, 1644335, 2567636, 3478873
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
COMMENTS
| A set-like molecular species is formed from the species of sets, E, through species addition, product and substitution.
|
|
|
REFERENCES
| G. Labelle and P. Leroux, Identities and enumeration: weighting connected components, Abstracts Amer. Math. Soc., 15 (1994), Meeting #896.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
|
LINKS
| G. Labelle and P. Leroux, An extension of the exponential formula in enumerative combinatorics
N. J. A. Sloane, Transforms
|
|
|
FORMULA
| Euler Transform of A007650. Define c(n): c(0)=0. c(k)=a(k), k>0. A007650=MOEBIUSi(c)-c. (Christian G. Bower (bowerc(AT)usa.net), Feb 23 2006)
|
|
|
CROSSREFS
| Cf. A000638, A007650.
Sequence in context: A140189 A165803 A204520 * A046152 A057239 A024541
Adjacent sequences: A007646 A007647 A007648 * A007650 A007651 A007652
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Simon Plouffe (simon.plouffe(AT)gmail.com)
|
| |
|
|
