login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Sum of the smallest sides of all acute integer triangles with perimeter n.
1

%I #51 Jun 16 2020 14:21:14

%S 0,0,1,0,1,2,1,2,4,5,4,6,8,6,13,11,18,17,19,23,22,30,29,32,37,40,54,

%T 49,63,63,65,73,79,94,90,98,113,110,138,127,151,154,161,181,180,210,

%U 209,216,240,247,279,269,297,320,318,348,359,402,396,401,441,440

%N Sum of the smallest sides of all acute integer triangles with perimeter n.

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Integer_triangle">Integer Triangle</a>

%F a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} (1-sign(floor((n-i-k)^2/(i^2+k^2)))) * sign(floor((i+k)/(n-i-k+1))) k.

%t Table[Sum[Sum[k*(1 - Sign[Floor[(n - i - k)^2/(i^2 + k^2)]]) Sign[Floor[(i + k)/(n - i - k + 1)]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 100}]

%Y Cf. A070093.

%K nonn

%O 1,6

%A _Wesley Ivan Hurt_, May 15 2019