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1, 2, 3, 5, 6, 8, 9, 11, 13, 15, 16, 19, 20, 22, 24, 27, 28, 31, 32, 35, 37, 39, 40, 44, 46, 48, 50, 53, 54, 58, 59, 62, 64, 66, 68, 73, 74, 76, 78, 82, 83, 87, 88, 91, 94, 96, 97, 102, 104, 107, 109, 112, 113, 117, 119, 123, 125, 127, 128, 134, 135, 137, 140, 144, 146, 150
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(n)=number of pairs (c,d) of integers such that 0<c<=d and c*d<=n. [From Clark Kimberling, Jun 18 2011]
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MATHEMATICA
| f[n_, k_] := Floor[n/k] - Floor[(n - 1)/k]
g[n_, k_] := If[k^2 <= n, f[n, k], 0]
Table[Sum[f[n, k], {k, 1, n}], {n, 1, 100}] (* A000005 *)
t = Table[Sum[g[n, k], {k, 1, n}], {n, 1, 100}]
(* A038548 *)
a[n_] := Sum[t[[i]], {i, 1, n}]
Table[a[n], {n, 1, 100}] (* A094820 *)
(* from Clark Kimberling, Jun 18 2011 *)
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CROSSREFS
| Cf. A091626, A038548.
Sequence in context: A186225 A050172 A191877 * A093689 A097702 A082583
Adjacent sequences: A094817 A094818 A094819 * A094821 A094822 A094823
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 12 2004
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