A006092 Numbers beginning with letter 't' when spelled out in English.

2, 3, 10, 12, 13, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220

Offset: 1

Author

N. J. A. Sloane

Keywords

• word
• nonn

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).