A080430 a(n) = least odd number such that all pairwise sums a(i) + a(j), i < j <= n, are distinct.
1, 3, 5, 9, 15, 25, 41, 59, 77, 105, 147, 189, 255, 303, 363, 423, 515, 631, 747, 825, 951, 1061, 1091, 1215, 1433, 1595, 1723, 1929, 2119, 2321, 2613, 2771, 2869, 3111, 3443, 3667, 3867, 4115, 4521, 4993, 5397, 5747, 6121, 6393, 6663, 7257, 7423, 7735, 8279
Offset: 1
Keywords
Links
- Zak Seidov, Table of n, a(n) for n = 1..127
Crossrefs
Cf. A080429.
Programs
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Maple
S := {4}: A := array(1..10^4): for m from 1 to 10^4 do A[m] := 0 od: A[1] := 1: A[3] := 3: for n from 5 to 10^4-1 by 2 do mytest := 0: for j from 1 to n-2 by 2 do if A[j]>0 then if member(A[j]+n, S) then mytest := 1; break; fi:fi:od: if mytest=0 then A[n] := n; for j from 1 to n-2 by 2 do S := S union {A[j]+n} od: fi: od: for i from 1 to 10^4-1 by 2 do if A[i]>0 then printf(`%d,`, A[i]) fi: od: # James Sellers, Feb 26 2003 -
Mathematica
s = {1, 3}; s2 = {4}; k = 5; Do[Label[kk]; If[Intersection[s + k, s2] == {}, s2 = Flatten[{s + k, s2}]; AppendTo[s, k]]; k = k + 2; If[k < 10000, Goto[kk]], {1}]; s (* Zak Seidov, Dec 23 2014 *)
Extensions
More terms from James Sellers, Feb 26 2003