Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I M1088 #30 Mar 14 2015 19:28:52
%S 2,4,8,12,16,20,26,32,40,44,54,64,72,80,92,104,116,128,140,152,164,
%T 180,196,212,228,244,262,280,298,316,338,360,382,404,426,448,470,492,
%U 514,536,562,588,614,644,674,704,734
%N Restricted postage stamp problem with n denominations and 2 stamps.
%C a(n) = largest span (range) attained by a restricted additive 2-basis of length n; an additive 2-basis is restricted if its span is exactly twice its largest element. - _Jukka Kohonen_, Apr 23 2014
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H J. Kohonen, <a href="http://cs.uwaterloo.ca/journals/JIS/VOL17/Kohonen2/kohonen5.html">A Meet-in-the-Middle Algorithm for Finding Extremal Restricted Additive 2-Bases</a>, J. Integer Seq., 17 (2014), Article 14.6.8.
%H J. Kohonen, <a href="http://arxiv.org/abs/1503.03416">Early Pruning in the Restricted Postage Stamp Problem</a>, arXiv:1503.03416 [math.NT] preprint (2015).
%H S. S. Wagstaff, Jr., <a href="http://dx.doi.org/10.1007/BFb0062717">Additive h-bases for n</a>, pp. 302-327 of Number Theory Carbondale 1979, Lect. Notes Math. 751 (1982).
%e a(10)=44: For example, the basis {0, 1, 2, 3, 7, 11, 15, 17, 20, 21, 22} has 10 nonzero elements, and all integers between 0 and 44 can be expressed as sums of two elements of the basis. Currently n=10 is the only known case where A006638 differs from A001212. - _Jukka Kohonen_, Apr 23 2014
%Y Cf. A001212.
%K nonn
%O 1,1
%A _N. J. A. Sloane_.
%E Definition improved by _Jukka Kohonen_, Apr 23 2014
%E Extended up to a(41) from Kohonen (2014), by _Jukka Kohonen_, Apr 23 2014
%E Extended up to a(47) from Kohonen (2015), by _Jukka Kohonen_, Mar 14 2015