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A180224 a(n+1) is the least k such that 1/(a(n)+1) + 1/(a(n)+2) + ... + 1/k > 1, with a(1) = 1. 1
1, 4, 12, 34, 94, 257, 700, 1904, 5177, 14074, 38258, 103997, 282695, 768446, 2088854, 5678095, 15434664, 41955768, 114047603, 310013528, 842704141, 2290707355, 6226788179, 16926165158, 46010087176, 125068383898, 339971115266, 924137304830, 2512065642722, 6828502388509 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..30.

FORMULA

a(n) = A103762(a(n-1) + 1) for n > 1. - Jinyuan Wang, Mar 05 2020

EXAMPLE

1/2 = 0.5, 1/2 + 1/3 = 0.833..., 1/2 + 1/3 + 1/4 = 1.0833... > 1, so a(2) = 4.

PROG

(PARI) default(realprecision, 10^5); e=exp(1);

lista(nn) = {my(k=1); print1(k); for(n=2, nn, print1(", ", k=floor(e*k+(e+1)/2+(e-1/e)/(24*(n+1/2))))); } \\ Jinyuan Wang, Mar 05 2020

CROSSREFS

Cf. A103762.

Sequence in context: A307305 A176753 A248873 * A293005 A173412 A079818

Adjacent sequences:  A180221 A180222 A180223 * A180225 A180226 A180227

KEYWORD

nonn

AUTHOR

Pierre CAMI, Aug 16 2010

EXTENSIONS

Name clarified by and more terms from Jinyuan Wang, Mar 05 2020

STATUS

approved

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Last modified March 7 03:08 EST 2021. Contains 341862 sequences. (Running on oeis4.)