A385721 Primes in A386964.

2, 23, 2357, 2357137939171, 2357137939171373, 23571379391713739, 2357137939171373917139397137, 2357137939171373917139397137937179, 235713793917137391713939713793717991737391137913793911739171337137177939739397199113939713, 2357137939171373917139397137937179917373911379137939117391713371371779397393971991139397137971939131

Offset: 1

Author

Rajsaday Dutt, Aug 04 2025

Keywords

• nonn
• base

Comments

From Michael S. Branicky, Aug 12 2025: (Start)

Also, numbers b(k) such that b(k) is prime, where b(1) = prime(1) = 2, b(n) = 10*b(n-1) + (prime(n) mod 10), as noted in Comments in A276481.

a(n) has A276481(n) digits, so a(14) has 7923 digits. (End)

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..13

Crossrefs

Cf. A007652, A276481, A386964.

Programs

Mathematica

a[1]=2; a[n_]:=10a[n-1]+Mod[Prime[n], 10];Select[Array[a,100],PrimeQ] (* James C. McMahon, Aug 16 2025 *)

Formula

a(n) = A386964(A276481(n)). - Michael S. Branicky, Aug 12 2025