21161

Appears in sequences

• Number of (s(0),s(1),...,s(n)) such that every s(i) is a nonnegative integer, s(0) = 1, |s(1) - s(0)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also sum of numbers in row n+1 of the array T defined in A026120.at n=10A026135
• Numbers whose base-2 representation has exactly 13 runs.at n=30A043580
• Numbers k such that 189*2^k-1 is prime.at n=36A050846
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, 0, 0), (0, -1, 1), (1, 1, -1), (1, 1, 1)}.at n=8A149623
• a(n) = 40*n^2 + 1.at n=23A158602
• Smallest numbers containing exactly n smaller numbers when written as English number names.at n=21A159453
• Least semiprime for which n-1 iterations of "Look & Say" (A045918) all yield semiprimes, but not the n-th iteration.at n=5A205300
• a(n) = n*(7*n^2 - 3*n - 1)/3.at n=21A214659
• Smallest k such that A257743(k)=n.at n=28A257744
• Number of partitions of 2*n into exactly n prime powers (including 1).at n=45A341154