A085701 - OEIS

A085701

Smallest multiple of n such that a(n) + a(n-1) is a squarefree number.

1, 2, 3, 4, 10, 12, 7, 8, 9, 10, 11, 12, 26, 56, 15, 16, 17, 18, 19, 20, 21, 22, 69, 24, 50, 52, 27, 28, 29, 30, 31, 64, 33, 34, 35, 36, 37, 76, 39, 40, 82, 84, 43, 44, 45, 46, 47, 48, 49, 100, 51, 52, 53, 54, 55, 56, 57, 58, 177, 60, 122, 124, 63, 64, 65, 66, 67, 136, 69, 70, 71

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OFFSET

1,2

COMMENTS

The sequence ends with a(319)=1276, since 320k + 1276 is divisible by 4 for all k.

LINKS

Table of n, a(n) for n=1..71.

MATHEMATICA

smn[{n_, a_}]:=Module[{k=1}, While[!SquareFreeQ[a+k*n], k++]; {n+1, k*n}]; NestList[ smn, {1, 1}, 80][[All, 2]] (* Harvey P. Dale, Jul 02 2022 *)

CROSSREFS

Sequence in context: A259561 A087460 A082866 * A051627 A023725 A250051

Adjacent sequences: A085698 A085699 A085700 * A085702 A085703 A085704