A176096 Smallest prime p = p(n) containing exactly n strings "13" (n = 1, 2, ...).
13, 13313, 1313813, 131313113, 13131313133, 1131313131313, 131313131313139, 13131313131313913, 1313131311313131313, 113131313131313131313, 13131313131313133131313, 1313131131313131313131313
Offset: 1
Examples
n = 1: prime(6) = 13 is 1st term of sequence prime(12268) = 131303 > 21313 = prime(2392) > 13313 = prime(1581) = p(2), 2nd term of sequence prime(857198) = 13131317 > 4131313 = prime(291796) > prime(102949) = 1341313 > 1313813 = prime() = p(3), 3rd term of sequence n = 13: 131131313131313131313131313 a 27-digit prime is 13th term of sequence
References
- E. I. Ignatjew, Mathematische Spielereien, Urania Verlag Leipzig/Jena/Berlin 1982
- B. A. Kordemski: Koepfchen, Koepfchen! Mathematik zur Unterhaltung, Urania Verlag Leipzig/Jena/Berlin 1965