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 A056138 Number of ways in which n can be the shorter leg (shortest side) of an integer-sided right-angled triangle. 1

%I

%S 0,0,1,0,1,1,1,1,2,1,1,2,1,1,3,2,1,2,1,3,3,1,1,4,2,1,3,3,1,3,1,3,4,1,

%T 3,5,1,1,4,5,1,3,1,3,5,1,1,7,2,2,4,3,1,3,3,5,4,1,1,9,1,1,5,4,4,4,1,3,

%U 4,3,1

%N Number of ways in which n can be the shorter leg (shortest side) of an integer-sided right-angled triangle.

%F a(n) = A046079(n)-A056137(n) = A046081(n)-A046080(n)-A056137(n)

%o (PARI) a(n)=my(b);sum(c=n+2,n^2\2+1,issquare(c^2-n^2,&b) && n<b) \\ _Charles R Greathouse IV_, Jul 07 2013

%Y Cf. A009004, A055525, A055527.

%K nonn

%O 1,9

%A _Henry Bottomley_, Jun 15 2000

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Last modified October 15 09:22 EDT 2019. Contains 328026 sequences. (Running on oeis4.)