%I A004277
%S A004277 1,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,
               50,
%T A004277 52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94,96,
%U A004277 98,100,102,104,106,108,110,112,114,116,118,120,122,124,126,128,130,132
%N A004277 1 together with positive even numbers.
%C A004277 Also number of non-attacking bishops on n X n board. - Koksal Karakus 
               (karakusk(AT)hotmail.com), May 27 2002
%C A004277 Engel expansion of e^(1/2) (see A006784 for definition) [when offset 
               by 1] - Henry Bottomley (se16(AT)btinternet.com), Dec 18 2000
%C A004277 Numbers n such that a 2n-group (i.e. a group of order 2n) has subgroup 
               C_2. - Lekraj Beedassy (blekraj(AT)yahoo.com), Oct 14 2004
%C A004277 Image of 1/(1-2x) under the mapping g(x)->g(x/(1+x^2)). - Paul Barry 
               (pbarry(AT)wit.ie), Jan 16 2005
%C A004277 Position of n in A113322: A113322(a(n-1)) = n for n>0. - Reinhard Zumkeller 
               (reinhard.zumkeller(AT)gmail.com), Oct 26 2005
%C A004277 Incrementally largest terms in the continued fraction for e. - Nick Hobson 
               Jan 11 2007
%C A004277 Or, the differences of two consecutive primes (without repetition). [From 
               Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 09 2009]
%H A004277 E. Friedman, <a href="http://www.stetson.edu/~efriedma/mathmagic/0201.html">
               Math. Magic</a>
%H A004277 <a href="Sindx_El.html#Engel">Index entries for sequences related to 
               Engel expansions</a>
%F A004277 G.f.: (1+x^2)/(1-x)^2 - Paul Barry (pbarry(AT)wit.ie), Feb 28 2003
%F A004277 Inverse binomial transform of Cullen numbers A002064. a(n)=2n+0^n. - 
               Paul Barry (pbarry(AT)wit.ie), Jun 12 2003
%F A004277 a(n)=sum{k=0..floor(n/2), binomial(n-k-1)(-1)^k*2^(n-2k)}; - Paul Barry 
               (pbarry(AT)wit.ie), Jan 16 2005
%F A004277 Equals binomial transform of [1, 1, 1, -1, 1, -1, 1,...]. - Gary W. Adamson 
               (qntmpkt(AT)yahoo.com), Jul 15 2008
%F A004277 E.g.f.: 1+x*sinh(x) (aerated sequence). [From Paul Barry (pbarry(AT)wit.ie), 
               Oct 11 2009]
%Y A004277 Cf. A004275, A008486, A030978.
%Y A004277 Cf. A097134.
%Y A004277 INVERT transformation yields A098182 without A098182(0). [From R. J. 
               Mathar (mathar(AT)strw.leidenuniv.nl), Sep 11 2008]
%Y A004277 Cf. A000040. [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 
               09 2009]
%Y A004277 Sequence in context: A119432 A005843 A076032 this_sequence A122080 A105360 
               A084564
%Y A004277 Adjacent sequences: A004274 A004275 A004276 this_sequence A004278 A004279 
               A004280
%K A004277 easy,nonn
%O A004277 0,2
%A A004277 N. J. A. Sloane (njas(AT)research.att.com).