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A259053 Number of triangles with sides pairwise relatively prime and one maximal side being n; permutations of sides are not considered distinct. 1
1, 0, 0, 0, 1, 0, 3, 2, 4, 1, 11, 2, 17, 6, 8, 9, 32, 6, 42, 12, 22, 15, 64, 12, 56, 25, 49, 25, 107, 12, 124, 51, 64, 45, 86, 27, 180, 59, 91, 45, 225, 30, 250, 81, 96, 87, 302, 55, 263, 82 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,7
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
triangles[n_] := Module[{count = 0},
For[a = 1, a <= n, a++,
For[b = a, b <= n, b++,
If[(a + b > n) && CoprimeQ[a, b, n], count++]]];
count];
triangles[#] & /@ Range[50]
PROG
(PARI) a(n)=if(n==1, return(1)); sum(a=3, n-2, if(gcd(a, n)==1, my(an=a*n); sum(b=max(a+1, n-a+1), n-1, gcd(an, b)==1))) \\ Charles R Greathouse IV, Jun 29 2015
CROSSREFS
First differences of A259446.
Sequence in context: A134029 A117623 A145690 * A161911 A139583 A073314
KEYWORD
nonn
AUTHOR
Vincent J. Matsko, Jun 29 2015
STATUS
approved

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Last modified June 17 18:36 EDT 2024. Contains 373463 sequences. (Running on oeis4.)