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A229882 Squarefree oblong numbers. 2
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 (list; graph; refs; listen; history; text; internal format)
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 A127517

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

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Last modified July 24 20:26 EDT 2021. Contains 346273 sequences. (Running on oeis4.)