A075813 - OEIS

A075813

Palindromic even numbers with exactly 2 prime factors (counted with multiplicity). Equivalently, palindromic numbers of the form 2*p with p prime.

4, 6, 22, 202, 262, 454, 626, 818, 838, 878, 898, 20302, 20602, 22322, 22522, 22622, 22822, 24142, 24842, 26662, 26762, 28682, 41014, 41414, 41614, 41714, 43034, 43234, 43534, 43634, 45454, 45554, 45754, 47074, 47374, 47774, 49094, 49394

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

4=2^2, 6=2*3 and 22=2*11 are palindromic, even and have exactly 2 prime factors.

MAPLE

test := proc(n) local d; d := convert(n, base, 10); return ListTools[Reverse](d)=d and numtheory[bigomega](n)=2; end; a := []; for n from 2 to 50000 by 2 do if test(n) then a := [op(a), n]; end; od; a;

MATHEMATICA

Select[Range[50000], EvenQ[#]&&PalindromeQ[#]&&PrimeOmega[#]==2&] (* Harvey P. Dale, Oct 16 2024 *)

CROSSREFS

Cf. A001747.

Sequence in context: A062940 A061596 A061597 * A107952 A004032 A123046

Adjacent sequences: A075810 A075811 A075812 * A075814 A075815 A075816

KEYWORD

nonn,base

AUTHOR

Jani Melik, Oct 13 2002

EXTENSIONS

Edited by Dean Hickerson, Oct 21 2002

STATUS

approved