A081472 a(n) = the smallest (n+k) such that the LCM of numbers from (n+1) to (n+k) is a multiple of n.

2, 4, 6, 8, 10, 9, 14, 16, 18, 15, 22, 16, 26, 21, 20, 32, 34, 27, 38, 25, 28, 33, 46, 32, 50, 39, 54, 35, 58, 35, 62, 64, 44, 51, 42, 45, 74, 57, 52, 48, 82, 49, 86, 55, 54, 69, 94, 64, 98, 75, 68, 65, 106, 81, 66, 64, 76, 87, 118, 65, 122, 93, 72, 128, 78, 77, 134, 85, 92, 77

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

a(4) = 8 because lcm(5) = 5, lcm(5, 6) = 30 and lcm(5, 6, 7) = 210 are not divisible by 4, but lcm(5, 6, 7, 8) = 840 is.

Mathematica

dv[n_]:=Module[{k=1}, While[!Divisible[LCM@@Range[n+1, n+k], n], k++]; k+n]; Array[dv, 70] (* Harvey P. Dale, Sep 13 2013 *)

Crossrefs

Cf. A081467, A081468, A081469, A081470, A081471, A061243.

a(n) = n + A034699(n)

Sequence in context: A055952 A061243 A079431 * A097660 A238898 A176995

Adjacent sequences: A081469 A081470 A081471 * A081473 A081474 A081475

Keyword

nonn

Author

Amarnath Murthy, Mar 23 2003

Extensions

More terms from David Wasserman, Mar 24 2003

Status

approved