21049

Appears in sequences

• Pseudoprimes to base 6.at n=40A005937
• a(n) = dot_product(1,2,...,n)*(7,8,...,n,1,2,3,4,5,6).at n=35A026049
• Numbers n such that 229*2^n-1 is prime.at n=34A050866
• Products of three distinct happy primes A035497.at n=28A154717
• Triangle t(n,k) read by rows: fibonomial ratios c(n)/(c(k)*c(n-k)) where c are partial products of a generalized Fibonacci sequence with multiplier m=3.at n=38A172347
• Triangle t(n,k) read by rows: fibonomial ratios c(n)/(c(k)*c(n-k)) where c are partial products of a generalized Fibonacci sequence with multiplier m=3.at n=42A172347
• A double product sequence based on a=3;f(n,a)=f(n-1,a)+a*f(n-2,a).at n=29A173918
• A double product sequence based on a=3;f(n,a)=f(n-1,a)+a*f(n-2,a).at n=34A173918
• A product triangle sequence based on:a=3;f(n, a) = f(n - 1, a) + a*f(n - 2, a); c(n,a)=If[n == 0, 1, Product[f(i, a)*f(i + 1, a), {i, 1, n}]]; t(n,m,a)=If[Floor[n/2] >= m, c(n, a)/c(n - m, a), c(n, a)/c(m, a)].at n=29A174412
• A product triangle sequence based on:a=3;f(n, a) = f(n - 1, a) + a*f(n - 2, a); c(n,a)=If[n == 0, 1, Product[f(i, a)*f(i + 1, a), {i, 1, n}]]; t(n,m,a)=If[Floor[n/2] >= m, c(n, a)/c(n - m, a), c(n, a)/c(m, a)].at n=34A174412
• Fibonacci sequence beginning 10, 7.at n=17A190996
• Smallest k>0 such that (5^n-k)*5^n-1 and (5^n-k)*5^n+1 are a twin prime pair or 0 if no such k exists.at n=49A212488
• Euler pseudoprimes to base 6: composite integers such that abs(6^((n - 1)/2)) == 1 mod n.at n=26A262053
• Number of 4 X n binary arrays with rows lexicographically nondecreasing and columns lexicographically nondecreasing and row sums nondecreasing and column sums nonincreasing.at n=30A266937
• Number of ways to write n as an ordered sum of seven positive Fibonacci numbers (with a single type of 1).at n=41A357694
• Number of multisets whose right half (inclusive) sums to n.at n=27A360671
• Expansion of g^2/(1 + x^3*g), where g = 1+x*g^3 is the g.f. of A001764.at n=7A391296