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
Examples
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.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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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)]);
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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 *)