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A227290 Repeatedly map numbers to number of letters in English name (A005589); sequence gives first number that needs n steps to get to 4. 1

%I #21 Jul 26 2013 15:20:40

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

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

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

%C 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

%e "eleven" has 6 letters, "six" has 3 letters, "three" has 5 letters, "five" has 4 letters.

%e So a(4)=11, as A005589^4(11)=4 and 11 is the first such number.

%e But a(3)=1, because "one" is the same length as "six".

%Y Cf. A016037.

%K nonn,word

%O 0,1

%A _Roland Kneer_, Jul 05 2013

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Last modified March 29 10:22 EDT 2024. Contains 371268 sequences. (Running on oeis4.)