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A177063 Number of Pythagorean triangles with area n. 2
0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,210

COMMENTS

The first term > 1 is a(210) = 2, cf. A009127, A055193 and A024407. Up to there the sequence coincides with the characteristic function of A009112. The triangles are not necessarily primitive.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index to sequences related to Pythagorean triples

PROG

(PARI) a(n)=my(N=1+#n=divisors(2*n)); sum(i=1, N\2, issquare(n[i]^2+n[N-i]^2));

CROSSREFS

Cf. A009111, A009127, A177021.

Sequence in context: A011679 A011682 A318880 * A302049 A078926 A324824

Adjacent sequences:  A177060 A177061 A177062 * A177064 A177065 A177066

KEYWORD

nonn

AUTHOR

M. F. Hasler, Dec 09 2010

EXTENSIONS

Secondary offset added by Antti Karttunen, Nov 24 2017

STATUS

approved

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Last modified August 10 12:38 EDT 2020. Contains 336379 sequences. (Running on oeis4.)