0,1

These molecules are composed of three types of atoms called 1, 2, and 3. The atoms are arranged linearly. Each atom shares bonds with the adjacent atoms. Each atom must carry as many bonds as the numeral representing it.

The members of this sequence are arranged in numerical order.

The reference states that the molecules "are numbered according to their complexity (length and type of atoms)", which is ambiguous.

For n > 2 there are fibonacci(n+1) members of length n.

Hintze and Adami arbitrarily chose a maximum length of 12, resulting in 608 total members; the last is 233333333332.

All terms are divisible by 11.

Arend Hintze and Christoph Adami, Evolution of complex modular biological networks. Page 3 defines the set of valid molecules; p. 17 lists a(0) through a(5) and a(607).

Using "-" to represent single bonds and "=" to represent double bonds, some members are a(0) = 1-1, a(4) = 2=3-1, and a(607) = 2=3-3=3-3=3-3=3-3=3-3=2.

2222 is not a member because the first 2 must share two bonds with the second 2, so the second 2 has no bonds left to share with the third 2.

Cf. A000045.

Sequence in context: A070022 A004940 A065816 this_sequence A109016 A084025 A061157

Adjacent sequences: A101142 A101143 A101144 this_sequence A101146 A101147 A101148

base,easy,fini,nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), Jun 03 2007

Edited and extended by David Wasserman (dwasserm(AT)earthlink.net), Mar 05 2008