A229882 Squarefree oblong numbers.

2, 6, 30, 42, 110, 182, 210, 462, 506, 870, 930, 1122, 1190, 1406, 1482, 1722, 1806, 2162, 3306, 3422, 3782, 4290, 4422, 4830, 4970, 5402, 6006, 6162, 6806, 7310, 7482, 8742, 8930, 10302, 10506, 11130, 11342, 11990, 12210, 12882, 13110, 14042, 15006, 16770, 17030

Offset

1,1

Comments

Oblong numbers that are squarefree numbers.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

Intersection of A002378 and A005117. - Joerg Arndt, Oct 03 2013

a(n) = A007674(n)^2 + A007674(n). - Charles R Greathouse IV, Oct 04 2013

Mathematica

Select[#*(# + 1) & /@ Range[150], SquareFreeQ] (* Amiram Eldar, Feb 22 2021 *)

Prog

(PARI) for(n=1, 1e4, if(issquarefree(n) && issquarefree(n+1), print1(n*(n+1)", "))) \\ Charles R Greathouse IV, Mar 18 2014

Crossrefs

Cf. A002378, A005117, A007674, A061304.

Sequence in context: A090801 A166062 A100194 * A325986 A298759 A360680

Adjacent sequences: A229879 A229880 A229881 * A229883 A229884 A229885

Keyword

nonn,easy

Author

Irina Gerasimova, Oct 02 2013

Extensions

Wrong term removed and more terms added by Amiram Eldar, Feb 22 2021

Status

approved