0,2

Also number of non-attacking bishops on n X n board. - Koksal Karakus (karakusk(AT)hotmail.com), May 27 2002

Engel expansion of e^(1/2) (see A006784 for definition) [when offset by 1] - Henry Bottomley (se16(AT)btinternet.com), Dec 18 2000

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

Image of 1/(1-2x) under the mapping g(x)->g(x/(1+x^2)). - Paul Barry (pbarry(AT)wit.ie), Jan 16 2005

Position of n in A113322: A113322(a(n-1)) = n for n>0. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 26 2005

Incrementally largest terms in the continued fraction for e. - Nick Hobson Jan 11 2007

Or, the differences of two consecutive primes (without repetition). [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 09 2009]

Equals (1, 2, 2, 2,...) convolved with (1, 0, 2, 0, 2, 0, 2,...). [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Mar 03 2010]

E. Friedman, Math. Magic

Index entries for sequences related to Engel expansions

G.f.: (1+x^2)/(1-x)^2 - Paul Barry (pbarry(AT)wit.ie), Feb 28 2003

Inverse binomial transform of Cullen numbers A002064. a(n)=2n+0^n. - Paul Barry (pbarry(AT)wit.ie), Jun 12 2003

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

Equals binomial transform of [1, 1, 1, -1, 1, -1, 1,...]. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 15 2008

E.g.f.: 1+x*sinh(x) (aerated sequence). [From Paul Barry (pbarry(AT)wit.ie), Oct 11 2009]

Cf. A004275, A008486, A030978.

Cf. A097134.

INVERT transformation yields A098182 without A098182(0). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 11 2008]

Cf. A000040. [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 09 2009]

Sequence in context: A119432 A005843 A076032 this_sequence A122080 A105360 A084564

Adjacent sequences: A004274 A004275 A004276 this_sequence A004278 A004279 A004280

easy,nonn,new

N. J. A. Sloane (njas(AT)research.att.com).