A208770 - OEIS

A208770

Areas of triangle ABC, if it can be split by two straight lines through A and B, into 4 parts all with integer areas.

6, 12, 15, 18, 20, 21, 24, 28, 30, 35, 36, 40, 42, 44, 45, 48, 52, 54, 56, 60, 63, 65, 66, 70, 72, 75, 77, 78, 80, 84, 85, 88, 90, 91, 95, 96, 99, 100, 104, 105, 108, 110, 112, 117, 119, 120

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..46.

FORMULA

n = a+b+c+d, if d = b*c*(2*a+b+c)/(a^2-b*c) is positive integer.

EXAMPLE

For n=6, some triangle with that area can be divided by 2 straight lines through A and B, into 4 parts with areas (2,1,1,2) or with areas (3,1,1,1). A triangle with area 12 can be divided into parts (2,1,2,7), (3,1,3,5), (4,2,2,4) and (6,2,2,2). Triangles with area 13 or 14 cannot be divided in this way.

CROSSREFS

Sequence in context: A114304 A175952 A278638 * A219095 A107487 A092671

Adjacent sequences: A208767 A208768 A208769 * A208771 A208772 A208773

KEYWORD

nonn,more

AUTHOR

Dragan Krejakovic, Mar 01 2012

STATUS

approved