0,6

Row sums of A105522. Row sums of inverse of A105438.

First column of number triangle A106180.

G.f.: (1+2x-sqrt(1+4x^2))/(2x)

a(n)=0^n+sin(pi*(n-2)/2)(C((n-1)/2)(1-(-1)^n)/2);

Cf. A097331, A090192.

Adjacent sequences: A105520 A105521 A105522 this_sequence A105524 A105525 A105526

Sequence in context: A078153 A104035 A115333 this_sequence A126120 A090192 A097331

easy,sign

Paul Barry (pbarry(AT)wit.ie), Apr 11 2005