A209269 - OEIS

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A209269

a(1) = 1 and, for n >= 2, a(n) is the least integer such that the numerator of the continued fraction [a(1),a(2),...,a(n)] is a perfect square.

1, 3, 2, 5, 43, 522, 1104509, 60248974744, 2075863890266492169136, 10942918579397694712648387271683911959312808, 30436613005235318097155473477154291219175029919236526500330140104415890363628017565032

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..11.

FORMULA

a(n) = (A086541(n) - A086541(n-2)) / A086541(n-1) (n >= 3). - Hiroaki Yamanouchi, Oct 03 2014

PROG

(PARI) v=[1]; for(k=1, 6, m=1; while(issquare(contfracpnqn(concat(v, [m]))[1, 1])==0, m++); v=concat(v, [m])); a(n)=if(n<2, 1, v[n]);

CROSSREFS

Cf. A086541

Sequence in context: A005265 A005266 A005267 * A373562 A244823 A286157

Adjacent sequences: A209266 A209267 A209268 * A209270 A209271 A209272

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 15 2013

EXTENSIONS

a(8)-a(11) from Max Alekseyev, Mar 18 2023

STATUS

approved