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A046465
Numbers k such that the concatenation of numbers from 1 to k is the product of 6 primes (not necessarily distinct).
1
11, 12, 18, 19, 22, 24, 32, 33, 39, 49, 57, 65, 70, 71, 75, 76, 78, 79, 81, 83, 85, 87, 88, 91, 95, 96, 99, 105, 110
(list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Table of n, a(n) for n=1..29.
Patrick De Geest, Normal Smarandache Concatenated Numbers, Prime factors from 1 up to n
M. Fleuren, Smarandache Factors and Reverse factors
Carlos Rivera, Puzzle 8. Primes by Listing, The Prime Puzzles & Problems Connection.
MATHEMATICA
Select[Range[100], PrimeOmega@FromDigits@Flatten@IntegerDigits@Range@# == 6 &] (* Robert Price, Oct 11 2019 *)
CROSSREFS
Cf. A046460.
Sequence in context: A070605 A087450 A176650 * A134926 A105744 A092096
Adjacent sequences: A046462 A046463 A046464 * A046466 A046467 A046468
KEYWORD
nonn,base,hard,more
AUTHOR
Patrick De Geest, Aug 15 1998
EXTENSIONS
a(12)-a(29) from Sean A. Irvine, Apr 10 2021
STATUS
approved

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Last modified October 5 00:39 EDT 2024. Contains 376527 sequences.
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