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A184830
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a(n) = largest k such that A000961(n+1) = A000961(n) + (A000961(n) mod k), or 0 if no such k exists.
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3
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0, 0, 2, 3, 3, 6, 7, 7, 9, 10, 15, 15, 15, 21, 23, 25, 27, 30, 27, 33, 39, 39, 45, 45, 47, 57, 58, 61, 63, 69, 67, 77, 79, 77, 81, 93, 99, 99, 105, 105, 105, 117, 123, 126, 125, 125, 135, 129, 147, 145, 151, 159, 165, 165, 167, 177, 171, 189, 189, 195
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OFFSET
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1,3
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COMMENTS
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LINKS
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EXAMPLE
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For n = 1 we have A000961(1) = 1, A000961(2) = 2; there is no k such that 2 - 1 = 1 = (1 mod k), hence a(1) = 0.
For n = 3 we have A000961(3) = 3, A000961(4) = 4; 2 is the largest k such that 4 - 3 = 1 = (3 mod k), hence a(3) = 2; a(3) = 3 - 1 = 2.
For n = 24 we have A000961(24) = 49, A000961(25) = 53; 45 is the largest k such that 53 - 49 = 4 = (49 mod k), hence a(24) = 45; a(24) = 49 - 4 = 45.
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MAPLE
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else
0;
end if;
end proc:
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MATHEMATICA
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nmax = 10000;
ppmax = 12*nmax; (* increase prime power max coef 12 in case of overflow *)
A000961 = Join[{1}, Select[Range[2, ppmax], PrimePowerQ]];
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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