OFFSET
1,1
LINKS
Sebastian Petzelberger, Table of n, a(n) for n = 1..10000
Carlos Rivera, PP&P Puzzle 24: Primes in several bases
EXAMPLE
11233 = 324413_5 and 324413_10 is composite; 11233 = 44515_7 and 44515_10 is composite; 11233_10 itself is composite. Interpreted in base 2, 3, 4, 6, 8, and 9 the result is prime. Hence 11233 is in this sequence.
PROG
(PARI) is(n)=!isprime(n) && sum(b=2, 9, isprime(fromdigits(digits(n, b))))==6 \\ Charles R Greathouse IV, Apr 23 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Sebastian Petzelberger, Mar 25 2015
STATUS
approved