cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A301408 Repeatedly map numbers to the number of letters in the English name (include spaces, but no hyphens and no "and"s); sequence gives smallest nonnegative integer that needs exactly n iterations to get to 4.

Original entry on oeis.org

4, 0, 3, 1, 11, 23, 123, 101323373373
Offset: 0

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Examples

			Since "twenty three" has 12 letters (including the space), "twelve" has 6 letters, "three" has 5 letters, "four" has four letters, and no other smaller nonnegative integer maps to 4 in exactly 5 iterations, then a(5) = 23.
		

References

  • M. Ecker, Number play, calculators, and card tricks: Mathemagical black holes, in E. Berlekamp and T. Rodgers, eds., The Mathemagician and Pied Puzzler: A Collection in Tribute to Martin Gardner, A. K. Peters, 1999, pp. 41-52.

Crossrefs

Cf. A227290, A005589, A016037 (these do not count the spaces in the names of larger integers).