18738638

Appears in sequences

• Companion Pell numbers: a(n) = 2*a(n-1) + a(n-2), a(0) = a(1) = 2.at n=19A002203
• Numerators of continued fraction convergents to sqrt(8).at n=18A041010
• Numbers k such that (k^2 + 4)/2 is a square.at n=9A077444
• Duplicate of A077444.at n=9A077461
• a(n) = floor((1+sqrt(2))^n).at n=19A080039
• Start with the sequence S(0)={1,1} and for k>0 define S(k) to be I(S(k-1)) where I denotes the operation of inserting, for i=1,2,3..., the term a(i)+a(i+1) between any two terms for which 4a(i+1)<=5a(i). The listed terms are the initial terms of the limit of this process as k goes to infinity.at n=37A082981
• Expansion of (1+x^2)/(1-2*x-x^2).at n=19A099425
• a(n) = -(u^n-1)*(v^n-1) with u = 1+sqrt(2), v = 1-sqrt(2).at n=18A129744
• a(1) = 2, a(2) = 8; a(n) = 2 a(n - 1) + a(n - 2) - 4*(n mod 2).at n=18A162484