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

1,2

Links

Zak Seidov, Table of n, a(n) for n = 1..127

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 A. 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 *)

Crossrefs

Cf. A080429.

Sequence in context: A029877 A207641 A147425 * A053523 A053522 A053521

Adjacent sequences: A080427 A080428 A080429 * A080431 A080432 A080433

Keyword

nonn

Author

Amarnath Murthy, Feb 20 2003

Extensions

More terms from James A. Sellers, Feb 26 2003

Status

approved