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A186145
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Rank of n^2 when {i^2: i>=1} and {j^3: j>=1} are jointly ranked with i^2 before j^3 when i^2=j^3. Complement of A186146.
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14
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1, 3, 5, 6, 7, 9, 10, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 24, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 40, 42, 43, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 67, 68, 69, 70, 71, 72, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 88, 89, 90, 91, 92, 93, 95, 96, 97, 98, 99, 100, 102, 103, 104, 105, 106, 107, 108, 110, 111, 112, 113, 114, 115, 116, 118, 119, 120, 121
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OFFSET
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1,2
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COMMENTS
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Suppose u,v,p,q are positive integers and 0<|d|<1. Let
a(n)=n+floor(((u*n^p-d)/v)^(1/q)),
b(n)=n+floor(((v*n^q+d)/u)^(1/p)).
When the disjoint sets {u*i^p} and {v*j^q+d} are jointly ranked, the rank of u*n^p is a(n) and the rank of v*n^q+d is b(n). Therefore a and b are a pair of complementary sequences. Choosing d carefully serves as a basis for two types of adjusted joint rankings of non-disjoint sets {u*i^p} and {v*j^q}.
First, if we place u*i^p before v*j^q whenever u*i^p=v*j^q, then with 0<d<1, a(n) and b(n) are the ranks of u*n^p and v*j^q, respectively. For the second type, if we place u*i^p after v*j^q whenever u*i^p=v*j^q, then with -1<d<0, a(n) and b(n) are ranks of u*n^p and v*j^q, respectively.
More generally, if u=h/k and v=s/t are positive rational numbers in lowest terms, then a(n) and b(n) are the respective ranks of u*n^p and v*n^q, adjusted as described above, according as d=1/(2kq) or d=-1/(2kq). Examples: A186148-A186159.
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LINKS
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FORMULA
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a(n)=n+floor((n^2-1/2)^(1/3)) (A186145).
b(n)=n+floor((n^3+1/2)^(1/2)) (A186146).
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EXAMPLE
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Write the squares and cubes thus:
1..4....9..16..25....36..49..64..81
1.....8...........27.........64.....
Replace each by its rank, where ties are settled by ranking the square before the cube:
a=(1,3,5,6,7,9,10,11,13,...)
b=(2,4,8,12,...)
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MATHEMATICA
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d=1/2;
a[n_]:=n+Floor[(n^2-d)^(1/3)]; (* rank of n^2 *)
b[n_]:=n+Floor[(n^3+d)^(1/2)]; (* rank of n^3+1/2 *)
Table[a[n], {n, 1, 100}]
Table[b[n], {n, 1, 100}]
(* end *)
(* A more general program follows. *)
d=1/2; u=1; v=1; p=2; q=3;
h[n_]:=((u*n^p-d)/v)^(1/q);
a[n_]:=n+Floor[h[n]]; (* rank of u*n^p *)
k[n_]:=((v*n^q+d)/u)^(1/p);
b[n_]:=n+Floor[k[n]]; (* rank of v*n^q *)
Table[a[n], {n, 1, 100}]
Table[b[n], {n, 1, 100}]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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