A384636 Triprimes that are the concatenation of three consecutive primes in reverse order.

1175, 231917, 434137, 534743, 595347, 10310197, 107103101, 137131127, 149139137, 163157151, 167163157, 179173167, 223211199, 239233229, 251241239, 269263257, 281277271, 293283281, 311307293, 349347337, 383379373, 401397389, 419409401, 421419409, 449443439, 457449443, 487479467, 491487479

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(3) = 434137 is a term because it is the concatenation in reverse order of the three consecutive primes 37, 41 and 43, and 434137 = 11 * 61 * 647 is the product of three primes.

Maple

cat3:= proc(a, b, c)
  (a*10^(1+ilog10(b))+b)*10^(1+ilog10(c))+c
end proc:
select(t -> numtheory:-bigomega(t) = 3, [seq(cat3(ithprime(i+2), ithprime(i+1), ithprime(i)), i=1..100)]);

Mathematica

p3[p_]:=FromDigits[Join[IntegerDigits[Prime[p+2]], IntegerDigits[Prime[p+1]], IntegerDigits[Prime[p]]]]; Select[Array[p3, 100], PrimeOmega[#]==3&] (* James C. McMahon, Jun 09 2025 *)

Crossrefs

Cf. A014612, A383114, A384638.

Sequence in context: A204756 A027485 A204755 * A202199 A233870 A237774

Adjacent sequences: A384633 A384634 A384635 * A384637 A384638 A384639

Keyword

nonn,base

Author

Will Gosnell and Robert Israel, Jun 05 2025

Status

approved