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.

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

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%I A227290 #21 Jul 26 2013 15:20:40
%S A227290 4,0,3,1,11,23,323,1103323373373373373373373373373
%N A227290 Repeatedly map numbers to number of letters in English name (A005589); sequence gives first number that needs n steps to get to 4.
%C A227290 Based on the observation by Diane Karloff that the trajectory of A005589 always converges to 4.
%C A227290 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 A227290 "eleven" has 6 letters, "six" has 3 letters, "three" has 5 letters, "five" has 4 letters.
%e A227290 So a(4)=11, as A005589^4(11)=4 and 11 is the first such number.
%e A227290 But a(3)=1, because "one" is the same length as "six".
%Y A227290 Cf. A016037.
%K A227290 nonn,word
%O A227290 0,1
%A A227290 _Roland Kneer_, Jul 05 2013