815616

Appears in sequences

• Let Product[1+Sum[b(i,j) x^(i*j),{i,1,Infinity}],{j,1,Infinity}]=1+Sum[c(n) x^n,{n,1,Infinity}], where b(i,j) is plus or minus one and c(n) is plus or minus one or zero. Furthermore, let b(1,1)=1 (for definiteness). Then, for a given n, a(n) is the number of ways in which the coefficients b(i,j) i<=n, j<=n can be chosen.at n=11A088857
• E.g.f.: 2*x*(1-log(1+2*x))/(2-log(1+2*x)).at n=9A109589
• a(n) = ((8 + sqrt(8))^n + (8 - sqrt(8))^n)/2.at n=6A145303
• The number of positive integer sequences of length n with no duplicate substrings (forward or backward) of length greater than 1 and a minimal sum (= A282168(n)).at n=18A284432