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A007970 Rhombic numbers. 10
3, 7, 8, 11, 15, 19, 23, 24, 27, 31, 32, 35, 40, 43, 47, 48, 51, 59, 63, 67, 71, 75, 79, 80, 83, 87, 88, 91, 96, 99, 103, 104, 107, 115, 119, 120, 123, 127, 128, 131, 135, 136, 139, 143, 151, 152, 160, 163, 167, 168, 171, 176, 179 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A000037; A007968(a(n))=2; A002145 is a subsequence;

A191856(n) = A007966(a(n)); A191857(n) = A007967(a(n));

a(n) = A191856(n)*A191857(n). [Reinhard Zumkeller, Jun 18 2011]

LINKS

J. H. Conway, On Happy Factorizations, J. Integer Sequences, Vol. 1, 1998, #1.

CROSSREFS

Every number belongs to exactly one of A000290, A007969, A007970.

Sequence in context: A078466 A047528 A069122 * A134258 A028972 A153030

Adjacent sequences:  A007967 A007968 A007969 * A007971 A007972 A007973

KEYWORD

nonn

AUTHOR

J. H. Conway (conway(AT)math.princeton.edu)

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Last modified February 14 18:09 EST 2012. Contains 205663 sequences.