OFFSET
1,1
REFERENCES
Bellamy, O. S.; Cadogan, C. C. Subsets of positive integers: their cardinality and maximality properties. Proceedings of the Tenth Southeastern Conference on Combinatorics, Graph Theory and Computing (Florida Atlantic Univ., Boca Raton, Fla., 1979), pp. 167--178, Congress. Numer., XXIII-XXIV, Utilitas Math., Winnipeg, Man., 1979. MR0561043 (82b:10006)
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
PROG
(Haskell)
import Data.List (elemIndices)
a212909 n = a212909_list !! (n-1)
a212909_list = map (+ 1) $ elemIndices 4 a212813_list
-- Reinhard Zumkeller, May 30 2012
CROSSREFS
KEYWORD
nonn,fini
AUTHOR
N. J. A. Sloane, May 30 2012
STATUS
approved