A215403 Isotopes of Conway's audioactive transuranic elements, in reversed lexicographic order.

312211322212221121123222114, 13112221133211322112211213322114, 312211322212221121123222115, 13112221133211322112211213322115, 312211322212221121123222116, 13112221133211322112211213322116, 312211322212221121123222117, 13112221133211322112211213322117

Offset: 1

Author

Reinhard Zumkeller, Aug 09 2012

Keywords

• nonn
• base

Comments

The transuranic elements Pu=31221132221222112112322211 and Np=1311222113321132211221121332211 are alternating prefixes;

n is suffix of a(2*n - 1) and of a(2*n) in decimal representation.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..500
• J. H. Conway, The weird and wonderful chemistry of audioactive decay, in T. M. Cover and Gopinath, eds., Open Problems in Communication and Computation, Springer, NY 1987, pp. 173-188.
• Kevin Watkins, Abstract Interpretation Using Laziness: Proving Conway's Lost Cosmological Theorem,
• Kevin Watkins, Proving Conway's Lost Cosmological Theorem, POP seminar talk, CMU, Dec 2006
• Eric Weisstein's World of Mathematics, Look and Say Sequence
• Wikipedia, Look-and-say sequence

Crossrefs

Cf. A119566, A213979.

Programs

Haskell

a215403 n k = a215403_list !! (n-1)
a215403_list = map (foldr (\d v -> 10 * v + d) 0) $
                   concatMap (\x -> map (x :) [plut', nept']) [4..] where
  plut' = [1,1,2,2,2,3,2,1,1,2,1,1,2,2,2,1,2,2,2,3,1,1,2,2,1,3]
  nept' = [1,1,2,2,3,3,1,2,1,1,2,2,1,1,2,2,3,1,1,2,3,3,1,1,2,2,2,1,1,3,1]