A371972 a(n) is the number of distinct areas of triangles with integer sides whose largest side is n.

1, 2, 4, 6, 9, 12, 16, 20, 25, 30, 36, 42, 49, 56, 64, 72, 81, 90, 100, 110, 120, 131, 144, 156, 168, 182, 196, 210, 225, 239, 256, 270, 288, 306, 321, 342, 361, 380, 399, 420, 441, 460, 484, 505, 527, 552, 576, 599, 623, 649, 673, 702, 729, 752, 781, 808, 840, 870, 900

Offset

1,2

Links

Table of n, a(n) for n=1..59.

Formula

a(n) <= A002620(n+1), with equality for n <= 20.

Prog

(PARI) A2(a, b, c) = {my(s=(a+b+c)/2); s*(s-a)*(s-b)*(s-c)};
a371972(n) = {my (A=List()); for(s2=1, n, for(s3=1, s2, if(s2+s3>n, listput(A, A2(n, s2, s3))))); #Set(A)};

Crossrefs

Cf. A002620, A371973, A371345.

Sequence in context: A194254 A086378 A088900 * A083392 A076921 A002620

Adjacent sequences: A371969 A371970 A371971 * A371973 A371974 A371975

Keyword

nonn

Author

Hugo Pfoertner, Apr 16 2024

Status

approved