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A037047 Starting at n, "say what you see"; sequence gives number of primes obtained before first composite number appears. 1
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

If n itself is a prime, it is not included in the count. - Antti Karttunen, Feb 13 2019

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

P. De Geest, World!Of Palindromic Primes

EXAMPLE

1 -> 11 (prime) -> 21 (composite), so a(1) = 1.

PROG

(PARI)

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

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

CROSSREFS

Cf. A005150, A036978, A045918.

Sequence in context: A258822 A064530 A307832 * A118917 A325045 A204293

Adjacent sequences:  A037044 A037045 A037046 * A037048 A037049 A037050

KEYWORD

nonn,base

AUTHOR

G. L. Honaker, Jr.

EXTENSIONS

More terms from Antti Karttunen, Feb 13 2019

STATUS

approved

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Last modified October 23 23:51 EDT 2019. Contains 328379 sequences. (Running on oeis4.)