A036978 -id:A036978 - cp's OEIS frontend

A036979 Primes arising in A036978.

11, 13, 17, 19, 1117, 1213, 1217, 23, 1319, 1511, 1613, 1619, 1811, 1913, 29, 31, 2113, 111211, 111217, 1123, 111317, 111611, 111913, 1129, 121013, 121019, 2213, 1223, 121711, 1229, 131011, 1321, 131113, 131213, 2311, 131413, 131519, 131611

Offset: 1

N. J. A. Sloane, G. L. Honaker, Jr.

Cf. A036978, A045918.

for(n=1, 999, isprime(p=A045918(n)) && print1(p", ")); \\ Michel Marcus, Dec 04 2020

Missing a(19) inserted by Sean A. Irvine, Dec 03 2020

A037047 Starting at n, "say what you see"; sequence gives number of primes obtained before first composite number appears.

Original entry on oeis.org

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

Offset: 1

G. L. Honaker, Jr.

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

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

Antti Karttunen, Table of n, a(n) for n = 1..20000
P. De Geest, World!Of Palindromic Primes

Cf. A005150, A036978, A045918.

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

More terms from Antti Karttunen, Feb 13 2019

cp's OEIS Frontend

A036979 Primes arising in A036978.

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