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%I #13 Feb 14 2019 07:46:34
%S 1,0,1,0,0,0,2,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,2,0,
%T 0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,
%U 1,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0
%N Starting at n, "say what you see"; sequence gives number of primes obtained before first composite number appears.
%C If n itself is a prime, it is not included in the count. - _Antti Karttunen_, Feb 13 2019
%H Antti Karttunen, <a href="/A037047/b037047.txt">Table of n, a(n) for n = 1..20000</a>
%H P. De Geest, <a href="http://www.worldofnumbers.com/palpri.htm">World!Of Palindromic Primes</a>
%e 1 -> 11 (prime) -> 21 (composite), so a(1) = 1.
%o (PARI)
%o A045918(a) = { my(c=1); for(j=2, #a=Vec(Str(a)), if(a[j-1]==a[j], a[j-1]=""; c++, a[j-1]=Str(c, a[j-1]); c=1)); a[#a]=Str(c, a[#a]); eval(concat(a)) }; \\ From A045918 by _M. F. Hasler_, Jan 27 2012
%o A037047(n) = if(1==n,n,my(c=0); while(1, n = A045918(n); if(isprime(n), c++, return(c)))); \\ _Antti Karttunen_, Feb 13 2019
%Y Cf. A005150, A036978, A045918.
%K nonn,base
%O 1,7
%A _G. L. Honaker, Jr._
%E More terms from _Antti Karttunen_, Feb 13 2019
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