1089155

Appears in sequences

• a(n) = Sum_{k=0..floor(n/4)} binomial(n-2k,2k).at n=31A005252
• Number of integers in {1, 2, ..., Fibonacci(n)} that are coprime to n.at n=31A074934
• Expansion of (1+x)/((1+x+x^2)(1-x-x^2)).at n=30A093040
• a(n) = floor[(phi + n mod 2)*a(n-1)], a(1)=1.at n=21A107857
• a(n) = b(k), where b(k) = Fibonacci(n-1) and k = floor( n*(1+sqrt(5))/2 ).at n=21A107858
• a(n+3) = 3*a(n+2) + 5*a(n+1) + a(n), a(0) = 1, a(1) = 2, a(2) = 11.at n=10A110679
• Number of nonnegative even integers <= Fibonacci(n).at n=32A147997
• a(n) = ceiling(Fibonacci(n)/2).at n=32A173173
• a(n) = (A000045(n)+A173432(n))/2.at n=31A173433
• Indices of centered pentagonal numbers (A005891) that are also triangular numbers (A000217).at n=10A254627
• p-INVERT of the positive integers, where p(S) = 1 - S^2.at n=15A290890
• a(n) = (Fibonacci(3*n-1) + 1)/2 for n >= 1.at n=10A292278
• a(n) = a(n-1) + a(n-2) - a(n-3) + a(n-4) for n > 4, where a(n)=0 for n < 4 and a(4) = 1.at n=34A293014
• Expansion of (1 - x + x^2)/((1 - x + x^2)^2 - 4*x^2).at n=15A376716
• Upper (1/2)-midsequence of (F(2n)) and (F(2n+1)), where F=A000045 (Fibonacci numbers); see Comments.at n=15A387779