21368

Appears in sequences

• Numbers k such that k, k+1, k+2 and k+3 have the same number of divisors.at n=28A006601
• The PDO(n) function (Partitions with Designated summands in which all parts are Odd): the sum of products of multiplicities of parts in all partitions of n into odd parts.at n=39A102186
• Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1), U=(1,2), or d=(1,-1) and have k hills of the form ud (a hill is either a ud or a Udd starting at the x-axis).at n=39A108433
• Indices where 2 occurs in A124151.at n=24A124401
• Numbers k such that 1 + Sum_{i=1..k} 2^(2*i-1) is prime.at n=29A127936
• a(n) is the total number of k-reverses of n.at n=20A180249
• Number of n X 7 arrays of the minimum value of corresponding elements and their horizontal or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..1 n X 7 array.at n=12A220031
• Number of partitions of n not containing 3*(number of parts) as a part.at n=36A238491
• Lexicographically earliest sequence of positive integers such that for any n > 0, the binary expansion of a(n) contains the binary expansion of k for k = 1..n and the binary expansion of a(n+1) is obtained by replacing a possibly empty substring of the binary expansion of a(n) by the binary expansion of n+1.at n=14A344184