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A330182
a(n) = n + floor(nr/t) + floor(ns/t), where r = Pi - 1, s = Pi, t = Pi + 1.
2
1, 4, 6, 9, 10, 13, 15, 18, 19, 22, 24, 27, 28, 31, 33, 36, 37, 40, 42, 45, 46, 49, 51, 54, 55, 58, 60, 63, 64, 67, 70, 72, 75, 76, 79, 81, 84, 85, 88, 90, 93, 94, 97, 99, 102, 103, 106, 108, 111, 112, 115, 117, 120, 121, 124, 126, 129, 130, 133, 136, 138
OFFSET
1,2
COMMENTS
This is one of three sequences that partition the positive integers. In general, suppose that r, s, t are positive real numbers for which the sets {i/r: i>=1}, {j/s: j>=1}, {k/t: k>=1} are disjoint. Let a(n) be the rank of n/r when all the numbers in the three sets are jointly ranked. Define b(n) and c(n) as the ranks of n/s and n/t. It is easy to prove that
a(n) = n + [ns/r] + [nt/r],
b(n) = n + [nr/s] + [nt/s],
c(n) = n + [nr/t] + [ns/t], where []=floor.
Taking r = Pi - 1, s = Pi, t = Pi + 1 yields a=A330181, b=A016789, c=A330182.
FORMULA
a(n) = n + floor(nr/t) + floor(ns/t), where r = Pi - 1, s = Pi, t = Pi + 1.
MATHEMATICA
r = Pi - 1; s = Pi; t = Pi + 1;
a[n_] := n + Floor[n*s/r] + Floor[n*t/r];
b[n_] := n + Floor[n*r/s] + Floor[n*t/s];
c[n_] := n + Floor[n*r/t] + Floor[n*s/t]
Table[a[n], {n, 1, 120}] (* A330181 *)
Table[b[n], {n, 1, 120}] (* A016789 *)
Table[c[n], {n, 1, 120}] (* A330182 *)
CROSSREFS
Sequence in context: A283794 A287003 A214068 * A330186 A284654 A010428
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jan 05 2020
STATUS
approved