21385

Appears in sequences

• Coefficients for step-by-step integration.at n=5A002398
• s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (F(2), F(3), ...), t = A001950 (upper Wythoff sequence).at n=22A024594
• Distinct odd elements in the 5-Pascal triangle A028313.at n=36A028319
• Odd elements to the right of the central elements of the 5-Pascal triangle A028313.at n=49A028325
• Number of partitions of n into parts not of the form 25k, 25k+2 or 25k-2. Also number of partitions with 1 part of size 1 and differences between parts at distance 11 are greater than 1.at n=43A036001
• Numbers whose sum of the squares of divisors is also a square number.at n=14A046655
• Number of nonempty subsets of {1,2,...,n} in which exactly 1/3 of the elements are <= sqrt(n).at n=17A048094
• a(n) = Fib(3*n)^2 - 2*Fib(3*n) + 4*Fib(3*n+1) + 5, where Fib = A000045.at n=4A049440
• Numbers k such that the sum of unitary divisors of k^2 is a square.at n=14A064498
• a(n) = binomial(n,4) - binomial(floor(n/2),4) - binomial(ceiling(n/2),4).at n=29A111385
• Smallest order of the cyclotomic polynomial whose maximal coefficient in absolute value is n.at n=10A136418
• RMS numbers: numbers n such that root mean square of divisors of n is an integer.at n=11A140480
• a(n) = 4*n^3 - 6*n^2 + 1.at n=18A141530
• Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a 2 X 2 elbow 1,1 1,2 2,1 in any orientation.at n=10A145941
• 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, 1, -1), (0, 0, 1), (1, 0, -1), (1, 0, 1)}.at n=8A150305
• a(n) = (n+3)^2*n/2 + 1.at n=33A154560
• Composite RMS numbers: composite numbers c such that root mean square of divisors of c is an integer.at n=7A158287
• a(n) = 66*n^2 + 1.at n=18A158689
• a(n) = 74*n^2 - 1.at n=16A158744
• Antidiagonal sums of the convolution array A213773.at n=12A213818