A140109 - OEIS

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A140109

Quartets of prime x, composites y, z and S for Heron's formula.

7, 15, 20, 42, 7, 24, 25, 84, 13, 14, 15, 84, 13, 84, 85, 546, 17, 8, 15, 60, 17, 9, 10, 36, 29, 20, 21, 210, 37, 12, 35, 210, 41, 9, 40, 180, 53, 45, 48, 1080, 73, 48, 55, 1320, 89, 39, 80, 1560, 97, 65, 72, 2340, 101, 20, 99, 990, 109, 60, 91, 2730, 113, 15, 112, 840

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Heron's formula (x+y+z)*(x+y-z)*(x+z-y)*(y+z-x)/16=S^2

LINKS

Table of n, a(n) for n=1..64.

EXAMPLE

The quartets are: (7, 15, 20, 42), (7, 24, 25, 84), (13, 14, 15, 84), etc.

CROSSREFS

Cf. A140385, A140391, A140384.

Sequence in context: A297853 A298050 A115783 * A064397 A214467 A151971