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 A174724 Sum_{k=1..n} Floor((k + 3*sqrt(k))/k). 0
 4, 7, 9, 11, 13, 15, 17, 19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Index entries for linear recurrences with constant coefficients, signature (2,-1). FORMULA (k+3*sqrt(k)) / k > = 1, (k+3*sqrt(k)) / k < 2 <=> k >=10, a(n) = 4 if n=1, a(n) = 2n + 3 if 2 <= n <= 9, a(n) = n + 12 if n>=10. MAPLE for n from 1 to 100 do: s:=0: for k from 1 to n do: s:=s+floor((k+3*sqrt(k))/k) : od:print(s):od: PROG (PARI) a(n)=if(n>8, n+12, 2*n+3-(n==1)) \\ Charles R Greathouse IV, Oct 27 2011 CROSSREFS Sequence in context: A159619 A272454 A207017 * A267873 A310943 A310944 Adjacent sequences:  A174721 A174722 A174723 * A174725 A174726 A174727 KEYWORD nonn,easy AUTHOR Michel Lagneau, Mar 28 2010 STATUS approved

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Last modified December 12 22:06 EST 2019. Contains 329963 sequences. (Running on oeis4.)