A048342 Numbers k such that the concatenation of the numbers 1, 2, ..., k is a product of distinct primes.

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

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: A072556 A047365 A353448 * 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