A049852 Concatenate "n" and "nextprime(n)".

12, 23, 35, 45, 57, 67, 711, 811, 911, 1011, 1113, 1213, 1317, 1417, 1517, 1617, 1719, 1819, 1923, 2023, 2123, 2223, 2329, 2429, 2529, 2629, 2729, 2829, 2931, 3031, 3137, 3237, 3337, 3437, 3537, 3637, 3741, 3841, 3941, 4041, 4143, 4243

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base

Comments

From Petros Hadjicostas, Nov 20 2019: (Start)

Version 1 of the "next prime" function is A007918: smallest prime >= n. PARI/GP's nextprime() is version 1.

Maple's nextprime() is the version 2 that appears in A151800: smallest prime > n. We use version 2 here. (End)

Examples

			From _Petros Hadjicostas_, Nov 20 2019: (Start)
a(1) = 12 because nextprime(1) = 2.
a(2) = 23 because nextprime(2) = 3.
a(3) = 35 because nextprime(3) = 5.
a(4) = 45 because nextprime(4) = 5.
...
a(10) = 1011 because nextprime(10) = 11.
a(11) = 1113 because nextprime(11) = 13.
... (End)
		

Crossrefs

Cf. A007918 (version 1 of nextprime), A151800 (version 2 of nextprime).

Programs

Maple

a:= n-> parse(cat(n, nextprime(n))):
seq(a(n), n=1..50);  # Alois P. Heinz, Nov 20 2019

PARI

a(n) = eval(concat(Str(n), Str(nextprime(n+1)))); \\ Michel Marcus, Jan 01 2017