A130610 Nonnegative values x of solutions (x, y) to the Diophantine equation x^2+(x+359)^2 = y^2.

0, 40, 901, 1077, 1281, 6160, 7180, 8364, 36777, 42721, 49621, 215220, 249864, 290080, 1255261, 1457181, 1691577, 7317064, 8493940, 9860100, 42647841, 49507177, 57469741, 248570700, 288549840, 334959064, 1448777077, 1681792581

Offset

1,2

Comments

Also values x of Pythagorean triples (x, x+359, y).

Corresponding values y of solutions (x, y) are in A159844.

For the generic case x^2+(x+p)^2 = y^2 with p = m^2-2 a (prime) number > 7 in A028871, see A118337.

lim_{n -> infinity} a(n)/a(n-3) = 3+2*sqrt(2).

lim_{n -> infinity} a(n)/a(n-1) = (363+38*sqrt(2))/359 for n mod 3 = {1, 2}.

lim_{n -> infinity} a(n)/a(n-1) = (293619+186550*sqrt(2))/359^2 for n mod 3 = 0.

Links

Table of n, a(n) for n=1..28.

Index entries for linear recurrences with constant coefficients, signature (1,0,6,-6,0,-1,1).

Formula

a(n) = 6*a(n-3)-a(n-6)+718 for n > 6; a(1)=0, a(2)=40, a(3)=901, a(4)=1077, a(5)=1281, a(6)=6160.

G.f.: x*(40+861*x+176*x^2-36*x^3-287*x^4-36*x^5) / ((1-x)*(1-6*x^3+x^6)).

a(3*k+1) = 359*A001652(k) for k >= 0.

Prog

(PARI) {forstep(n=0, 100000000, [1, 3], if(issquare(2*n^2+718*n+128881), print1(n, ", ")))}

Crossrefs

Cf. A159844, A028871, A118337, A130609, A001652, A156035 (decimal expansion of 3+2*sqrt(2)), A159845 (decimal expansion of (363+38*sqrt(2))/359), A159846 (decimal expansion of (293619+186550*sqrt(2))/359^2).

Sequence in context: A013348 A013349 A140220 * A279582 A004339 A172510

Adjacent sequences: A130607 A130608 A130609 * A130611 A130612 A130613

Keyword

nonn,easy

Author

Mohamed Bouhamida, Jun 17 2007

Extensions

Edited and two terms added by Klaus Brockhaus, Apr 30 2009

Status

approved