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 A056054 a(n) = smallest even number 2m such that value of odd harmonic series Sum_{j=0..m} 1/(2j) is > n. 5
 8, 62, 454, 3348, 24734, 182760, 1350428, 9978382, 73730824, 544801200, 4025566630, 29745137662, 219788490858, 1624029488844, 12000044999386, 88669005690160, 655180257281000, 4841163675961122, 35771629985782052 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers 2*m such that floor(f(m))=floor(f(m-1)) where f(m)= Sum_{j=1..m} ((2*j-1)/(2*j)). Examples: floor(f(1))=floor(1/2)=0; floor(f(2))=floor(1/2+2/3)=floor(1,25)=1, then 2*2=4 is not in the sequence; floor(f(3))=floor((1/2+3/4+4/5)=floor(2,083..)=2, then 2*3=6 is not in the sequence; floor((f(4))=floor(1/2+3/4+5/6+7/8)=floor(2,958..)=2, then 2*4=8 is the first term of the sequence. - Philippe Lallouet (philip.lallouet(AT)wanadoo.fr), Aug 15 2007 REFERENCES Calvin C. Clawson, Mathematical Mysteries, The Beauty and Magic of Numbers, Plenum Press, NY and London, 1996, page 64. LINKS FORMULA a(n) = 2*A002387(2n). The next term is approximately the previous term * e^2. MATHEMATICA s = 0; k = 2; Do[ While[s = N[s + 1/k, 24]; s <= n, k += 2]; Print[k]; k += 2, {n, 1, 12}] (* or assuming that the Mathematica coding in A002387 is correct then *) b[n_] := Module[{k = Floor[2a[2n]]}, If[ EvenQ[k], k, k + 1]]; Table[ b[n], {n, 19}] (* Robert G. Wilson v, Apr 17 2004 *) CROSSREFS Cf. A002387, A056053, A091463, A091464, A091465. Cf. A056054. Sequence in context: A269607 A296584 A198690 * A167251 A227439 A144143 Adjacent sequences:  A056051 A056052 A056053 * A056055 A056056 A056057 KEYWORD nonn AUTHOR Robert G. Wilson v, Jul 25 2000 and Jan 11 2004 STATUS approved

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Last modified July 30 17:21 EDT 2021. Contains 346359 sequences. (Running on oeis4.)