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A376902
Numbers k such that the concatenation of their prime factors with multiplicity, in some order, yields the k-th prime number.
0
21, 187, 5810, 17883, 3188109, 37880357
OFFSET
1,1
COMMENTS
This sequence allows the concatenation to be any permutation of the prime factors provided the digits of each prime factor are retained in their natural order.
So far, only k=187 factors concatenate in ascending order.
Next term if it exists > 1.2 * 10^9.
EXAMPLE
21 = 3*7 is a term since prime(21) = 73.
187 = 11*17 is a term since prime(187) = 1117.
5810 = 2*5*7*83 is a term since prime(5810) = 57283.
17883 = 3*3*1987 is a term since prime(17883) = 198733.
3188109 = 3*53*20051 is a term since prime(3188109) = 53320051.
CROSSREFS
Sequence in context: A303196 A274655 A274653 * A223090 A010827 A022713
KEYWORD
nonn,base,more
AUTHOR
Walter Scharold, Oct 08 2024
EXTENSIONS
a(6) from Sean A. Irvine, Oct 25 2024
STATUS
approved