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 A034757 a(1)=1, a(n) = smallest odd number such that all sums of pairs of (not necessarily distinct) terms in the sequence are distinct. 3
 1, 3, 7, 15, 25, 41, 61, 89, 131, 161, 193, 245, 295, 363, 407, 503, 579, 721, 801, 949, 1129, 1185, 1323, 1549, 1643, 1831, 1939, 2031, 2317, 2623, 2789, 3045, 3143, 3641, 3791, 4057, 4507, 4757, 5019, 5559, 5849, 6309, 6707, 7181, 7593 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(1) = 1, a(n) = least number such that every difference a(i)-a(j) is a distinct even number. - Amarnath Murthy, Apr 07 2004 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 FORMULA a(n) = 2*A005282(n)-1. (David Wasserman) EXAMPLE 5 is not in the sequence since 5+1 is already obtainable from 3+3, 9 is excluded since 1, 3 and 7 are in the sequence and would collide with 1+9 MATHEMATICA seq2={1, 3}; Do[le=Length[seq2]; t=Last[seq2]+2; While[Length[Expand[(Plus @@ (x^seq2) + x^t)^2]] < Pochhammer[3, le]/le!, t=t+2]; AppendTo[seq2, t], {20}]; Print@seq2 PROG (Haskell) a034757 = (subtract 1) . (* 2) . a005282  -- Reinhard Zumkeller, Dec 18 2012 CROSSREFS Cf. A025582, A051912, A055598. Sequence in context: A226471 A175510 A144643 * A291651 A078869 A011890 Adjacent sequences:  A034754 A034755 A034756 * A034758 A034759 A034760 KEYWORD nonn,nice,easy AUTHOR Wouter Meeussen, Jun 01 2000 EXTENSIONS An incorrect comment from Amarnath Murthy, also dated Apr 07 2004, has been deleted. Offset fixed by Reinhard Zumkeller, Dec 18 2012 STATUS approved

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Last modified October 19 08:15 EDT 2018. Contains 316337 sequences. (Running on oeis4.)