The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A005487 Starts 0, 4 and contains no 3-term arithmetic progression. (Formerly M3243) 11
 0, 4, 5, 7, 11, 12, 16, 23, 26, 31, 33, 37, 38, 44, 49, 56, 73, 78, 80, 85, 95, 99, 106, 124, 128, 131, 136, 143, 169, 188, 197, 203, 220, 221, 226, 227, 238, 247, 259, 269, 276, 284, 287, 302, 308, 310, 313, 319, 337, 385, 392, 397, 422, 434, 455, 466, 470 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS This is what would now be called the Stanley Sequence S(0,4). See A185256. REFERENCES R. K. Guy, Unsolved Problems in Number Theory, E10. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Chai Wah Wu, Table of n, a(n) for n = 0..10000 P. Erdos, V. Lev, G. Rauzy, C. Sandor, A. Sarkozy, Greedy algorithm, arithmetic progressions, subset sums and divisibility, Discrete Mathematics 200 (1999), pp. 119-135. R. A. Moy and D. Rolnick, Novel structures in Stanley sequences, arXiv:1502.06013 [math.CO], 2015. R. A. Moy and D. Rolnick, Novel structures in Stanley sequences, Discrete Math., 339 (2016), 689-698. A. M. Odlyzko and R. P. Stanley, Some curious sequences constructed with the greedy algorithm, 1978 MATHEMATICA ss[s1_, M_] := Module[{n, chvec, swi, p, s2, i, j, t1, mmm}, t1 = Length[s1]; mmm = 1000; s2 = Table[s1, {t1 + M}] // Flatten; chvec = Array[0&, mmm]; For[i = 1 , i <= t1 , i++, chvec[[s2[[i]] ]] = 1]; (* get n-th term *) For[n = t1+1 , n <= t1 + M , n++, (* try i as next term *) For[i = s2[[n-1]] + 1 , i <= mmm , i++, swi = -1; (* test against j-th term *) For[ j = 1 , j <= n-2 , j++, p = s2[[n - j]]; If[ 2*p - i < 0 , Break[] ]; If[ chvec[[2*p - i]] == 1 , swi = 1; Break[] ] ]; If[ swi == -1 , s2[[n]] = i; chvec[[i]] = 1; Break[] ] ]; If[ swi == 1 , Print["Error, no solution at n = ", n] ] ]; Table[s2[[i]], {i, 1, t1+M}] ]; ss[{0, 4}, 80] (* Jean-François Alcover, Sep 10 2013, translated from Maple program given in A185256 *) PROG (Python) A005487_list = [0, 4] for i in range(101-2):     n, flag = A005487_list[-1]+1, False     while True:         for j in range(i+1, 0, -1):             m = 2*A005487_list[j]-n             if m in A005487_list:                 break             if m < A005487_list[0]:                 flag = True                 break         else:             A005487_list.append(n)             break         if flag:             A005487_list.append(n)             break         n += 1 # Chai Wah Wu, Jan 05 2016 CROSSREFS Equals A033158(n+1)-1. Cf. A185256. Sequence in context: A032686 A074300 A047375 * A291741 A084087 A175903 Adjacent sequences:  A005484 A005485 A005486 * A005488 A005489 A005490 KEYWORD nonn,nice AUTHOR EXTENSIONS Name clarified by Charles R Greathouse IV, Jan 30 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 2 14:21 EDT 2020. Contains 334787 sequences. (Running on oeis4.)