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A228380
Positive integers N such that N = (p^2+q^2)*(r^2-s^2)/((p^2-q^2)*(r^2+s^2)) for some positive integers p,q,r,s.
3
1, 6, 13, 16, 18, 22, 23, 32, 33, 35, 36, 37, 41, 42, 43, 44, 45, 46, 50, 51, 53, 57, 58, 59, 60, 61, 63, 67, 69, 70, 74, 75, 77, 78, 79, 80, 83, 84, 85, 86, 88, 89, 90, 93, 94, 95, 96, 97, 98, 102, 104, 110, 112, 116, 117, 118, 119, 122, 123, 124, 126, 128, 132, 133, 134, 137, 138, 141, 142, 143, 152
OFFSET
1,2
COMMENTS
Integer N>1 belongs to this sequence if and only if the elliptic curve y^2 = x^3 - (N^2+1)*x^2 + N^2*x has positive rank.
PROG
(PARI) { isA228380(n) = ellanalyticrank(ellinit([0, -(n^2+1), 0, n^2, 0]))[1]; } /* Max Alekseyev, Sep 29 2015 */
CROSSREFS
Sequence in context: A353442 A140888 A053753 * A090068 A070899 A265756
KEYWORD
nonn
AUTHOR
Thomas Bokk, Aug 21 2013
EXTENSIONS
More terms from Max Alekseyev, Sep 29 2015
STATUS
approved