A087895 Primes p such that 10^p - 9^p is composite.

5, 13, 17, 23, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Mathematica

Select[Prime[Range[100]], !PrimeQ[10^#-9^#]&] (* Harvey P. Dale, Jun 21 2012 *)

Prog

(PARI) apmb(a, b, n) = { forprime(x=2, n, y=a^x-b^x; if(!ispseudoprime(y), print1(x", "); ) ) }

Crossrefs

Cf. A016189, A062576.

Primes k such that x^k - (x-1)^k is composite: A087489 (x=3), A087490 (x=4), A087685 (x=5), A087749 (x=6), A087759 (x=7), A087763 (x=8), A087894 (x=9), this sequence (x=10).

Sequence in context: A208883 A182078 A074278 * A092101 A105596 A037046

Adjacent sequences: A087892 A087893 A087894 * A087896 A087897 A087898

Keyword

nonn

Author

Cino Hilliard, Oct 26 2003

Extensions

Offset corrected by Mohammed Yaseen, Jul 19 2022

Status

approved