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A090194 Primes which when multiplied by their largest digit and 1 is added form another prime. 0
2, 43, 61, 263, 433, 461, 601, 641, 653, 661, 821, 857, 1061, 1063, 1187, 1361, 1423, 1487, 1613, 1811, 1871, 1877, 2063, 2081, 2143, 2161, 2621, 2801, 2837, 3061, 3163, 3581, 3623, 3631, 3643, 3851, 4561, 5087, 5261, 5381, 5623, 5807, 5861, 6011, 6053 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
In the prime sequence, select largest digit in each prime, multiply by the prime containing that digit, then add 1. If the result is another prime, add to sequence.
EXAMPLE
a(2)=43. Largest digit is 4. Multiply 43*4=172. 172+1=173, prime.
PROG
(PARI) isok(p) = isprime(p) && isprime(p*vecmax(digits(p))+1); \\ Michel Marcus, Jun 08 2014
CROSSREFS
Cf. A060418.
Sequence in context: A354726 A235473 A137415 * A107200 A079823 A107156
KEYWORD
easy,nonn,base
AUTHOR
Enoch Haga, Jan 22 2004
STATUS
approved

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Last modified February 29 10:33 EST 2024. Contains 370418 sequences. (Running on oeis4.)