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A272243 a(n) is the smallest number greater than a(n-1) that is expressible as the sum of two positive integers x + y = a(n), so that (x, y, a(n)) is an abc-hit, in more ways than a(n-1). 1
9, 81, 625, 729, 6561, 15625, 117649, 390625 (list; graph; refs; listen; history; text; internal format)



An abc-hit is a triple of coprime positive integers a, b, c  such that a + b = c and rad(abc) < c, where rad(n) is the largest squarefree number dividing n.


Table of n, a(n) for n=1..8.

Wikipedia, abc conjecture


Cf. A272242.

Cf. A120498, A130510 (possible values of c in abc-hits).

Cf. A225426 (triples of abc-hits).

Cf. A130512 (radicals of abc-hits).

Cf. A007947 (radicals).

Sequence in context: A223882 A267961 A213297 * A272242 A206728 A206857

Adjacent sequences:  A272240 A272241 A272242 * A272244 A272245 A272246




Vladimir Letsko, Apr 23 2016



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Last modified December 7 13:08 EST 2021. Contains 349581 sequences. (Running on oeis4.)