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A051493 Triangles with integer-length sides and perimeter n, not isomorphic to any triangle with integer-length sides and perimeter<n. 12
0, 0, 1, 0, 1, 0, 2, 1, 2, 1, 4, 2, 5, 2, 5, 4, 8, 4, 10, 6, 9, 6, 14, 8, 15, 9, 16, 12, 21, 11, 24, 16, 22, 16, 27, 18, 33, 20, 31, 24, 40, 23, 44, 30, 39, 30, 52, 32, 54, 35, 52, 42, 65, 38, 65, 48, 64, 49, 80, 48, 85, 56, 77, 64, 90, 58, 102, 72, 93, 69, 114, 72, 120, 81 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..74.

N. J. A. Sloane, Transforms

FORMULA

Moebius transform of A005044(n-3).

EXAMPLE

There are 3 triangles with integer-length sides and perimeter 9: 1-4-4, 2-3-4, 3-3-3. 3-3-3 is omitted because isomorphic to 1-1-1, so a(9)=2.

CROSSREFS

Sequence in context: A160974 A187718 A029196 * A029173 A002331 A060805

Adjacent sequences:  A051490 A051491 A051492 * A051494 A051495 A051496

KEYWORD

nonn

AUTHOR

Neil Fernandez

EXTENSIONS

Corrected and extended with formula by Christian G. Bower, Nov 15 1999.

STATUS

approved

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Last modified May 23 19:42 EDT 2013. Contains 225611 sequences.