

A070867


a(1) = a(2) = 1; a(n) = a(n1  a(n1)) + a(n1  a(n2)).


8



1, 1, 2, 2, 2, 4, 3, 4, 4, 4, 8, 5, 5, 8, 8, 6, 8, 12, 8, 11, 9, 9, 10, 13, 16, 9, 12, 20, 10, 12, 23, 12, 15, 21, 13, 17, 18, 19, 19, 22, 21, 19, 19, 26, 28, 16, 24, 33, 21, 26, 23, 36, 16, 26, 39, 16, 30, 33, 36, 19, 34, 31, 43, 23, 30, 32, 38, 23, 40, 26, 38, 43, 31, 31, 38, 44
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OFFSET

1,3


REFERENCES

S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 129.


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Nick Hobson, Python program for this sequence
Eric Weisstein's World of Mathematics, Wolfram Sequences
Index entries for Hofstadtertype sequences


MATHEMATICA

a[1] = a[2] = 1; a[n_] := a[n] = a[n  1  a[n  1]] + a[n  1  a[n  2]]; Table[ a[n], {n, 1, 80}]


PROG

(Haskell)
a070867 n = a070867_list !! (n1)
a070867_list = 1 : 1 : zipWith (+)
(map a070867 $ zipWith () [2..] a070867_list)
(map a070867 $ zipWith () [2..] $ tail a070867_list)
 Reinhard Zumkeller, May 31 2013


CROSSREFS

Cf. A005185, A226222.
Sequence in context: A166008 A194291 A194323 * A241164 A029157 A247301
Adjacent sequences: A070864 A070865 A070866 * A070868 A070869 A070870


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane, May 19 2002


EXTENSIONS

More terms from John W. Layman, May 21 2002
Erroneous comma in sequence corrected by Nick Hobson, Feb 17 2007


STATUS

approved



