OFFSET
1,4
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..106
B. Mazur, Arithmetic on curves, Bull. Amer. Math. Soc. 14 (1986), 207-259; see p. 225.
FORMULA
P=(0, 0), 2P=(1, 0); if kP=(a, b) then (k+1)P = (a' = (b^2 - a^3)/a^2, b' = -1 - b*a'/a).
a(n) = A028941(2n). - Seiichi Manyama, Nov 19 2016
a(n) = a(-n) = b(n)*b(n+3) - b(n+1)*b(n+2) for all n in Z where b(n) = A006720(n). - Michael Somos, Mar 23 2022
EXAMPLE
a(4) = 25 where 8P = (21/25, -69/125).
PROG
(PARI) a(n)=denominator(ellmul(E, [0, 0], 2*n)[1]) \\ Charles R Greathouse IV, Mar 23 2022
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
STATUS
approved