A157941 Numbers n divisible by the largest prime < sqrt(n), A007917(A000196(n-1)).

6, 8, 12, 15, 18, 21, 24, 30, 35, 40, 45, 56, 63, 70, 77, 84, 91, 98, 105, 112, 119, 132, 143, 154, 165, 182, 195, 208, 221, 234, 247, 260, 273, 286, 306, 323, 340, 357, 380, 399, 418, 437, 456, 475, 494, 513, 552, 575, 598, 621, 644, 667, 690, 713, 736, 759

Offset

1,1

Comments

Includes products of pairs of consecutive primes (A006094) as subsequence, equals A157942 with squares of primes (A001248) removed.

For a number < 5 the definition does not make much sense, since there is no prime < sqrt(4) = 2, so we don't consider them here.

Links

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

Mathematica

Select[Range[6, 800], Divisible[#, NextPrime[Sqrt[#], -1]]&] (* Harvey P. Dale, Sep 14 2019 *)

Prog

(PARI) for( n=5, 999, n % precprime(sqrtint(n-1)) | print1(n", "))

Crossrefs

Sequence in context: A315861 A027827 A328537 * A059611 A177085 A338370

Adjacent sequences: A157938 A157939 A157940 * A157942 A157943 A157944

Keyword

nonn

Author

M. F. Hasler, Mar 09 2009

Status

approved