A091922 Smallest m such that the decimal representation of the m-th prime interpreted in base n is not a prime, but prime in bases 10 <= b < n.

5, 10, 19, 18, 3801, 6167, 251529, 128019, 13780180, 20576

Offset: 11

Author

Reinhard Zumkeller, Feb 13 2004

Keywords

• nonn
• base
• more

Comments

No more terms <= 3*10^10. - Michael S. Branicky, Apr 02 2025

Crossrefs

Cf. A090862.

Programs

Mathematica

f[p_] := Module[{d = IntegerDigits[p], b = 11}, While[PrimeQ[FromDigits[d, b]], b++]; b]; a[n_] := Module[{p = 11, m = 5}, While[f[p] != n, p = NextPrime[p]; m++]; m]; Array[a, 8, 11] (* Amiram Eldar, Mar 28 2025 *)

Formula

A090862(a(n)) = n and A090862(m) <> n for m < a(n).

Extensions

a(17)-a(20) from Amiram Eldar, Mar 28 2025