18277

Appears in sequences

• a(n) = A007290(n+2) - 1 = 2*C(n+2,3) - 1.at n=37A108766
• Least K such that K*p(n)#-1 is the first of twin primes and 2*(K*p(n)#-1)+1 is prime, so K*p(n)#-1 is the first of twin primes and a Sophie Germain prime.at n=43A117848
• Sum of the altitudes of the leftmost valleys of all Dyck paths of semilength n (if path has no valley, then this altitude is taken to be 0).at n=10A143955
• 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), (0, 1, -1), (1, 0, 0)}.at n=8A150110
• G.f.: Sum_{n>=0} x^n * Sum_{k=0..n} binomial(n,k)^3 * x^k*(1-x)^(n-k).at n=10A217421
• Index sequence for limit-reversing A000002; see Comments.at n=44A245937
• Number of (n+1) X (5+1) 0..1 arrays with every 2 X 2 subblock antidiagonal maximum minus diagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal minimum nondecreasing vertically.at n=20A253394
• Triangle read by rows: T(n,k) = T(n,k-1) + T(n-1,k), T(n,0)=1, T(n,n) = T(n,n-1) + 1.at n=73A283054
• a(1) = a(2) = 1; a(n) = Sum_{1 < k < n, k not dividing n} a(k).at n=17A307856
• G.f. A(x) satisfies: 1 = Sum_{n>=0} x^n * ((1+x)^n - A(x))^(n+1), where A(0) = 0.at n=8A307940
• Expansion of Product_{k>=1} (Product_{j=1..k} (1 + x^(k*j))^k).at n=18A327064
• a(n) = Sum_{d|n} mu(n/d) * binomial(8*d,d) / (7*d+1).at n=4A346939
• E.g.f. satisfies A(x) = 1 + x*(exp(x*A(x)) - 1).at n=7A371115
• Triangle read by rows: the almost-Riordan array ( 1/(1-x) | 2/((1-x)*(1+sqrt(1-4*x))), (1-2*x-sqrt(1-4*x))/(2*x) ).at n=58A373744
• a(0) = 1; thereafter a(n) = 10*n^2 - 5*n + 2.at n=43A383466
• Least k > a(n-1) such that k + the sum of all previous terms = 0 (mod (k-2)), with a(1)=1 and a(2)=2.at n=19A390783