A166499 Concatenation of the rightmost digit of the n-th prime and the leftmost digit of the (n+1)th prime.

23, 35, 57, 71, 11, 31, 71, 92, 32, 93, 13, 74, 14, 34, 75, 35, 96, 16, 77, 17, 37, 98, 38, 99, 71, 11, 31, 71, 91, 31, 71, 11, 71, 91, 91, 11, 71, 31, 71, 31, 91, 11, 11, 31, 71, 92, 12, 32, 72, 92, 32, 92, 12, 12, 72, 32, 92, 12, 72, 12, 32, 33, 73, 13, 33, 73, 13, 73, 73

Offset: 1

Author

Zak Seidov, Oct 15 2009

Keywords

• base
• nonn

Comments

This is the comma transform of the primes (see A367360).

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A007652, A077648, A367360.

Programs

Maple

a:= n-> parse(cat(""||(ithprime(n))[-1],""||(ithprime(n+1))[1])):
seq(a(n), n=1..99);  # Alois P. Heinz, Nov 22 2023

Mathematica

With[{nmax=100},Map[10Mod[#[[1]],10]+IntegerDigits[#[[2]]][[1]]&,Partition[Prime[Range[nmax+1]],2,1]]] (* Paolo Xausa, Nov 24 2023 *)

Formula

a(n) = 10 * A007652(n) + A077648(n+1). - Alois P. Heinz, Nov 23 2023