A084991 Palindromes which can be written as a sum of two prime numbers.

4, 5, 6, 7, 8, 9, 22, 33, 44, 55, 66, 88, 99, 111, 141, 151, 181, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 313, 333, 404, 414, 424, 434, 444, 454, 464, 474, 484, 494, 505, 525, 565, 595, 606, 616, 626, 636, 646, 656, 666, 676, 686, 696, 808, 818, 828, 838, 848, 858, 868, 878, 888, 898, 909, 939, 949, 969, 979, 999

Offset

1,1

Comments

An odd palindrome k is in the sequence iff k-2 is prime. Assuming the Goldbach conjecture all even palindromes > 2 are in the sequence. - Sean A. Irvine, May 24 2026

Links

Table of n, a(n) for n=1..69.

Example

E.g. 181 is a palindrome and is 179 + 2. 179 and 2 are both prime.

Mathematica

With[{upto=1000}, Select[Select[Union[Total/@Tuples[Prime[ Range[ upto]], 2]], # == IntegerReverse[#]&], #<=upto&]] (* Harvey P. Dale, Nov 24 2017 *)

Crossrefs

Cf. A014091.

Sequence in context: A123977 A396184 A109602 * A356824 A099070 A288658

Adjacent sequences: A084988 A084989 A084990 * A084992 A084993 A084994

Keyword

nonn,base

Author

Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 27 2003

Extensions

More terms from Harvey P. Dale, Nov 24 2017

Status

approved