27690

Appears in sequences

• Triangle read by rows: T(n,k) is the number of Motzkin paths of length n with k valleys (n>=0, 0<=k<=floor(n/2)-1; a valley is a downstep followed by an upstep).at n=46A097885
• Numbers k such that k and 5*k, taken together, are pandigital.at n=23A115925
• Averages of twin prime pairs of the form : sum of two or more consecutive squares.at n=19A174716
• G.f.: Sum_{n>=0} x^n / (1-4*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k] * [Sum_{k=0..n} C(n,k)^2 * 4^k * x^k].at n=5A246510
• Numbers n = p * q, where n, p, and q together contain all 10 digits at least once.at n=17A253172
• a(n) = binomial(2*n,n) + Sum_{k=1..n} binomial(2*n-k,n-k)*Fibonacci(k).at n=8A277287
• Numbers k such that (88*10^k - 1)/3 is prime.at n=19A293537
• a(0) = a(1) = 1; a(n) = [x^n] Product_{k=1..n-1} (1 + x^a(k))/(1 - x^a(k)).at n=52A296387
• a(n) is the first average of a twin prime pair that is the sum of two distinct averages of twin prime pairs in exactly n ways.at n=46A358463
• Products of 5 distinct primes that are sandwiched between twin prime numbers.at n=15A376380
• Number of 2-colorings of length n without an arithmetic progression of length 5.at n=16A378197
• Consecutive states of the linear congruential pseudo-random number generator (419*s + 6173) mod 29282 when started at s=1.at n=23A385036
• a(n) is the largest integer k such that there is an integer m with exactly n nonunitary prime factors and m + A005117(i) is squarefree for 1 <= i <= k.at n=22A390138