a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 4. Also a(n) = T(n,n-4), where T is the array defined in A026082.
A026087
a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 4. Also a(n) = T(n,n-4), where T is the array defined in A026082.
Terms
- a(0) =1a(1) =2a(2) =9a(3) =28a(4) =93a(5) =294a(6) =925a(7) =2872a(8) =8856a(9) =27136a(10) =82764a(11) =251472a(12) =761774a(13) =2301924a(14) =6941898a(15) =20899680a(16) =62834397a(17) =188690634a(18) =566081421a(19) =1696873148a(20) =5082959517a(21) =15216909686a(22) =45532045749a(23) =136182428520a(24) =407160436435
External references
- oeis: A026087