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

1,1

Comments

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

Links

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

Example

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.

Mathematica

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

Crossrefs

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

Sequence in context: A091508 A075399 A079840 * A117698 A274057 A281135

Adjacent sequences: A231275 A231276 A231277 * A231279 A231280 A231281

Keyword

nonn,base,easy

Author

Jonathan Vos Post, Nov 06 2013

Extensions

More terms from Alois P. Heinz, Nov 07 2013

Status

approved