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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

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

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.

PROG

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

CROSSREFS

Cf. A140791, A380785.

Sequence in context: A332676 A142837 A064964 * A372402 A263670 A108826