A381372 Smaller of two consecutive primes p and q, both ending with 3, such that q-p = 10n, or -1 if no such primes exist.

283, 3413, 7253, 19333, 45893, 142993, 399283, 542603, 818723, 396733, 3240983, 10863973, 32788543, 8917523, 17652013, 92593183, 80935103, 92510963, 257789053, 481691513, 20831323, 47326693, 607010093, 1461724573, 387096133, 1496441363, 2298026803, 1855047163

Offset: 1

Author

Jean-Marc Rebert, Feb 23 2025

Keywords

• nonn
• base

Examples

			a(1) = 283, because 283 and 283 + 10 = 293 are two consecutive primes with the same last digit 3 and no smaller p has this property.
		

Crossrefs

Cf. A140791, A380785.

Programs

PARI

a(n) = my(p=3); while (!isprime(p) || ((nextprime(p+1)-p) != 10*n), p+=10); p; \\ Michel Marcus, Feb 24 2025