A268146 Twin prime pairs concatenated to their average in decimal representation (the greater twin prepended, the lesser appended).

543, 765, 131211, 191817, 313029, 434241, 616059, 737271, 103102101, 109108107, 139138137, 151150149, 181180179, 193192191, 199198197, 229228227, 241240239, 271270269, 283282281, 313312311, 349348347, 421420419, 433432431, 463462461, 523522521, 571570569, 601600599

Offset: 1

Author

Mikk Heidemaa, Jan 27 2016

Keywords

• nonn
• base
• easy

Comments

The greater prime of a twin prime pair is prepended and the lesser one is appended to their average (nonprime, interprime).

a(n) mod 3 = 0, (See A095958).

Examples

			a(1)=543: the greater prime {5} of the first twin prime pair {3, 5} is prepended and the lesser prime {3} is appended to their average {4}.
		

Crossrefs

Cf. A001097, A014574, A095958, A111875, A268145.

Programs

Mathematica

UpToN[k_]:=FromDigits//@ StringJoin//@ ToString/@ {#+1, #, #-1} &/@ Select[ Table[ Prime[n]+1, {n, 2, PrimePi[k]}], PrimeQ[#+1] &]; UpToN[10000]