21300

Appears in sequences

• a(n) = Sum_{t=0..n} g(t)*g(n-t) where g(t) = A002121(t).at n=46A002122
• McKay-Thompson series of class 30E for Monster.at n=37A058616
• a(n) = n*(8*n^2 - 5)/3.at n=20A063523
• a(0)=1; a(n) = sigma_1(n) + sigma_2(n) + sigma_3(n).at n=27A092347
• Number of nX3 0..1 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.at n=6A223222
• Number of nX7 0..1 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.at n=2A223226
• T(n,k)=Number of nXk 0..1 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.at n=38A223227
• T(n,k)=Number of nXk 0..1 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.at n=42A223227
• Number of partitions p of n not containing ceiling((min(p) + max(p))/2) as a part.at n=38A238485
• Answer to Red, Green and Blue Tiles Problem.at n=19A244281
• Even 14-gonal (or tetradecagonal) numbers.at n=30A270704
• First appearance of 2^n in A281130.at n=14A281131
• Number of maximal cliques in the n-polygon diagonal intersection graph.at n=27A291949
• Number of ways of converting one set of lists containing n elements to another set of lists containing n elements by removing the last element from one of the lists and either appending it to an existing list or treating it as a new list.at n=6A300159
• a(n) is the least k such that in the prime power factorization of k! the exponents of primes p_1, ..., p_n are odd, while the exponent of p_(n+1) is even.at n=10A321362
• G.f.: Sum_{n>=0} (x^(2*n-1) + 1)^n * x^n / (1 + x^(2*n+1))^(n+1), an even function.at n=51A326602
• Exponential (2,3)-perfect numbers: numbers m such that esigma(esigma(m)) = 3m, where esigma(m) is the sum of exponential divisors of m (A051377).at n=18A328132