

A045777


a(1)=1, a(2)=2; thereafter successive products of pairs of digits make further digits.


2



1, 2, 2, 4, 8, 3, 2, 2, 4, 6, 4, 8, 2, 4, 2, 4, 3, 2, 1, 6, 8, 8, 8, 1, 2, 6, 2, 6, 4, 8, 6, 4, 6, 4, 8, 2, 1, 2, 1, 2, 1, 2, 2, 4, 3, 2, 4, 8, 2, 4, 2, 4, 2, 4, 3, 2, 1, 6, 2, 2, 2, 2, 2, 2, 4, 8, 1, 2, 6, 8, 3, 2, 1, 6, 8, 8, 8, 8, 8, 1, 2, 6, 2, 6, 1, 2, 4, 4, 4, 4, 4, 8, 3, 2, 8, 2, 1, 2, 4, 8, 2, 4, 6, 2, 6
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OFFSET

1,2


COMMENTS

The numbers 0, 5, 7, and 9 never appear, but arbitrarily long sequences of 8's appear.


REFERENCES

Erich Friedman, Puzzles of the Week, http://www2.stetson.edu/~efriedma/mathpuzzle/


LINKS

T. D. Noe, Table of n, a(n) for n = 1..15212


EXAMPLE

1*2=2 2*2=4 2*4=8 4*8=32 8*3=24...


MATHEMATICA

t = {1, 2}; Do[ t = Join[t, IntegerDigits[t[[n1]] t[[n2]]]], {n, 3, 100}]; t


CROSSREFS

Sequence in context: A131199 A112059 A093094 * A136534 A121175 A183397
Adjacent sequences: A045774 A045775 A045776 * A045778 A045779 A045780


KEYWORD

easy,nonn,base


AUTHOR

Erich Friedman


STATUS

approved



