The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A235621 Primes whose base 9 representation also is the base 7 representation of a prime. 1
 2, 3, 5, 13, 23, 29, 37, 47, 59, 103, 109, 131, 167, 173, 181, 199, 211, 263, 283, 379, 419, 509, 541, 733, 787, 821, 859, 911, 919, 983, 1013, 1063, 1091, 1093, 1171, 1487, 1499, 1543, 1549, 1559, 1567, 1571, 1667, 1669, 1733, 1783, 1787, 1913, 1993, 2237, 2287, 2351, 2381, 2477, 2621 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This sequence is part of the two dimensional array of sequences based on this same idea for any two different bases b, c > 1. Sequence A235265 and A235266 are the most elementary ones in this list. Sequences A089971, A089981 and A090707 through A090721, and sequences A065720 - A065727, follow the same idea with one base equal to 10. LINKS EXAMPLE E.g., 13 = 14[9] and 14[7] = 11 both are prime. PROG (PARI) is(p, b=7, c=9)=vecmax(d=digits(p, c))

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 10 17:00 EDT 2021. Contains 342852 sequences. (Running on oeis4.)