A157936 Numbers n divisible by the least prime >= sqrt(n).

2, 4, 6, 9, 10, 15, 20, 25, 28, 35, 42, 49, 55, 66, 77, 88, 99, 110, 121, 130, 143, 156, 169, 170, 187, 204, 221, 238, 255, 272, 289, 304, 323, 342, 361, 368, 391, 414, 437, 460, 483, 506, 529, 551, 580, 609, 638, 667, 696, 725, 754, 783, 812, 841, 868, 899, 930

Offset

1,1

Comments

Contains A001248, A006094 and A157937 as subsequences.

Links

Table of n, a(n) for n=1..57.

Formula

A157936 = A157937 union A001248

Mathematica

dQ[n_]:=Module[{srn=Sqrt[n], x}, x=If [PrimeQ[srn], srn, NextPrime[srn]]; Divisible[n, x]]; Select [Range[1000], dQ]  (* Harvey P. Dale, Mar 12 2011 *)

Prog

(PARI) for( n=1, 1999, n % nextprime(sqrtint(n-1)+1) || print1(n", ")) /* sqrtint(n-1)+1 avoids rounding errors but can be replaced by sqrt(n) for small n */

Crossrefs

Cf. A157942.

Sequence in context: A219787 A331006 A065388 * A389102 A338348 A184978

Adjacent sequences: A157933 A157934 A157935 * A157937 A157938 A157939

Keyword

nonn

Author

M. F. Hasler, Mar 10 2009

Status

approved