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A123560
a(n) is the smallest integer such that 1/a(1)^2 + 1/a(2)^2 + ... + 1/a(n-1)^2 + 1/a(n)^2 is less than e.
0
1, 1, 2, 2, 3, 4, 5, 15, 67, 535, 8986, 912849, 1662587477, 81083409799344, 651628371908007046307, 17425286333232464262345491287814, 67473400772659322911375035883722405962101960016, 12550884311528115972476468763183847895333364390665475583839492176837589
OFFSET
1,3
FORMULA
a(n) = ceiling(sqrt(e - Sum_{i=1..n-1} 1/a(i)^2))
EXAMPLE
a(4) = 2 because the first three terms of the sequence are 1,1,2 and 2 is the smallest integer k such that 1/1^2 + 1/1^2 + 1/2^2 + 1/k^2 < e.
PROG
(PARI) \p150 \\ This is enough to print the first 17 terms correctly
my(l(x)=ceil(sqrt(1/x)), k=exp(1)); for(T=1, 17, print(l(k)); k=k-1/l(k)^2)
CROSSREFS
Sequence in context: A210642 A263140 A205006 * A060407 A083702 A074077
KEYWORD
nonn
AUTHOR
Hauke Worpel (hw1(AT)email.com), Nov 11 2006
STATUS
approved