A227290 Repeatedly map numbers to number of letters in English name (A005589); sequence gives first number that needs n steps to get to 4.

4, 0, 3, 1, 11, 23, 323, 1103323373373373373373373373373

Offset

0,1

Comments

Based on the observation by Diane Karloff that the trajectory of A005589 always converges to 4.

40311123323 (concatenation of the first seven terms) is the first time prime is obtained when concatenating k first initial terms of the sequence. - Jonathan Vos Post, Jul 06 2013, edited by Antti Karttunen, Jul 25 2013

Links

Table of n, a(n) for n=0..7.

Example

"eleven" has 6 letters, "six" has 3 letters, "three" has 5 letters, "five" has 4 letters.
So a(4)=11, as A005589^4(11)=4 and 11 is the first such number.
But a(3)=1, because "one" is the same length as "six".

Crossrefs

Cf. A016037.

Sequence in context: A280579 A086165 A301408 * A096303 A262695 A021252

Adjacent sequences: A227287 A227288 A227289 * A227291 A227292 A227293

Keyword

nonn,word

Author

Roland Kneer, Jul 05 2013

Status

approved