A210734 Primes p such that p + 1 or p - 1 is a concatenation of successive even numbers starting from 2.

3, 23, 2467, 246809, 246811, 24681012141619, 24681012141618202224262830323436384041, 24681012141618202224262830323436384042444649

Offset: 1

Author

Arkadiusz Wesolowski, May 10 2012

Keywords

• base
• nonn

Comments

a(9) has 625 digits, a(10) has 1476 digits, a(11) has 5048 digits, a(12) has 39024 digits.

Links

• Arkadiusz Wesolowski, Table of n, a(n) for n = 1..10
• G. L. Honaker, Jr. and Chris Caldwell, 24681...50451 (625-digits)
• Henri & Renaud Lifchitz, PRP Records

Crossrefs

Cf. A019520.

Programs

Mathematica

lst = {}; c = 0; Do[c = c*10^IntegerLength[n] + n; a = c - 1; If[PrimeQ[a], AppendTo[lst, a]]; b = c + 1; If[PrimeQ[b], AppendTo[lst, b]], {n, 2, 48, 2}]; lst