a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = sum of numbers in row n+1 of the array T defined in A026105. Also a(n) = T(n,n), where T is the array defined in A025564.
A025566
a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is a nonnegative integer, s(0) = 0, s(1) = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = sum of numbers in row n+1 of the array T defined in A026105. Also a(n) = T(n,n), where T is the array defined in A025564.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =3a(4) =8a(5) =22a(6) =61a(7) =171a(8) =483a(9) =1373a(10) =3923a(11) =11257a(12) =32418a(13) =93644a(14) =271219a(15) =787333a(16) =2290200a(17) =6673662a(18) =19478091a(19) =56930961a(20) =166613280a(21) =488176938a(22) =1431878079a(23) =4203938697a(24) =12353600427a(25) =36331804089a(26) =106932444885a(27) =314946659951a(28) =928213563878
External references
- oeis: A025566