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A048342 Numbers k such that the concatenation of the numbers 1, 2, ..., k is a product of distinct primes. 3
1, 3, 4, 5, 7, 10, 11, 13, 14, 15, 19, 21, 22, 23, 29, 30, 31, 33, 34, 37, 38, 39, 41, 42, 43, 46, 47, 49, 51, 55, 57, 58, 59, 61, 65, 66, 67, 69, 70, 73, 74, 77, 78, 79, 82, 83, 86, 87, 91, 93, 94, 95, 97, 101, 102, 103, 105, 106, 109, 110, 111, 113, 114, 115 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..64.

Patrick De Geest, Normal Smarandache Concatenated Numbers, Prime factors from 1 up to n

Eric Weisstein's World of Mathematics, Consecutive Number Sequences

CROSSREFS

Cf. A007908.

Sequence in context: A105148 A072556 A047365 * A159560 A288427 A030502

Adjacent sequences:  A048339 A048340 A048341 * A048343 A048344 A048345

KEYWORD

nonn,hard,base

AUTHOR

Patrick De Geest, Feb 15 1999

EXTENSIONS

More terms from Sean A. Irvine, Jun 13 2021

STATUS

approved

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Last modified August 1 16:01 EDT 2021. Contains 346393 sequences. (Running on oeis4.)