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

Author

Irina Gerasimova, Oct 02 2013

Keywords

• nonn
• easy

Comments

Oblong numbers that are squarefree numbers.

Links

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

Crossrefs

Cf. A002378, A005117, A007674, A061304.

Programs

Mathematica

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

PARI

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

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

Extensions

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