OFFSET
1,1
COMMENTS
The next 179 terms are all the numbers from 221 to 399. Assuming that '1000' is spelled 'one thousand', the following terms are the numbers in the intervals [x*1000 , x*1000+999] where x runs over all elements a(1),..,a(225) occurring up to there. Then the numbers in the intervals [x*10^6, (x+1)*10^6-1] appear, where x again runs over all preceding terms. M. F. Hasler, Mar 23 2011
REFERENCES
Archimedeans Problems Drive, Eureka, 48 (1988), pages 55, 56, 99.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
FORMULA
Let g_k(x) = (x^(2k) - x^(4k) + x^(10k) - x^(11k) + x^(12k) - x^(14k) + x^(20k) - x^(40k) + x^(200k) - x^(400k))/(1-x). Then the g.f. of the characteristic function of this sequence is sum(j>=0, g_{1000^j}(x).
CROSSREFS
KEYWORD
word,nonn
AUTHOR
STATUS
approved