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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
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, 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, 4, 3, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

LINKS

Table of n, a(n) for n=1..71.

FORMULA

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

PROG

(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

CROSSREFS

Cf. A009004, A055525, A055527.

Sequence in context: A145574 A182579 A290737 * A067594 A089533 A284312

Adjacent sequences:  A056135 A056136 A056137 * A056139 A056140 A056141

KEYWORD

nonn

AUTHOR

Henry Bottomley, Jun 15 2000

STATUS

approved

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Last modified September 18 12:00 EDT 2019. Contains 327170 sequences. (Running on oeis4.)