A231278 Not necessarily palindromic primes of which initial and terminal digits are identical, as written in base 3.

2, 111, 212, 1011, 1101, 1121, 2012, 2122, 10121, 10211, 11001, 11201, 12011, 12121, 12211, 20012, 20102, 20122, 21002, 21022, 22102, 22122, 22212, 101001, 101021, 101111, 102101, 102121, 110021, 110111, 110221, 111121, 111211, 112001, 112201, 120011, 120121

Offset: 1

Author

Jonathan Vos Post, Nov 06 2013

Keywords

• nonn
• base
• easy

Comments

Base-3 analog of what A077652 is for base 10.

Examples

			a(3) = 212, which starts and ends with "2", and in base 3 means 2*(3^2) + 1*(3^1) + 2*(3^0) = 18 + 3 + 2 = 23 (base 10), which is prime.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..2500

Crossrefs

Cf. A000030, A000040, A007089, A077652, A227858.

Programs

Mathematica

FromDigits/@Select[IntegerDigits[#,3]&/@Prime[Range[100]],#[[1]]==#[[-1]]&] (* Harvey P. Dale, Oct 23 2022 *)

Extensions

More terms from Alois P. Heinz, Nov 07 2013