19387

Properties

Appears in sequences

• a(n) = Sum_{k=0..m} (k+1) * A026022(n, m-k), where m=n for n=0,1 and m = floor((n+3)/2) for n >= 2.at n=13A027299
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 86 ones.at n=19A031854
• Number of "rooted index-functional forests" (Riffs) on n nodes. Number of "rooted odd trees with only exponent symmetries" (Rotes) on 2n+1 nodes.at n=9A061396
• Row sums in triangle A081994.at n=23A081997
• Primes p such that p + 2^2, p + 4^2 and p + 6^2 are also primes.at n=30A092475
• Primes p of Erdos-Selfridge class 4+ with largest prime factor of p+1 not of class 3+.at n=12A129472
• G.f. satisfies: A(x) = x/(1 - A(A(A(x)))).at n=6A140094
• Primes congruent to 50 mod 61.at n=36A142848
• a(n) = n^3 - (3*(n+3))^2.at n=31A153259
• Primes of the form 7*x^2 - 5*y^2, where x and y are successive natural numbers.at n=35A176557
• Number of n X 4 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.at n=6A197369
• Number of nX7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.at n=3A197372
• T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.at n=48A197373
• T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.at n=51A197373
• Triangle of coefficients of polynomials v(n,x) jointly generated with A210741; see the Formula section.at n=50A210742
• Number of nondecreasing -2..2 vectors of length n whose dot product with some lexicographically greater or equal nondecreasing -2..2 vector equals n.at n=23A226416
• First primes of arithmetic progressions of 5 primes each with the common difference 30.at n=35A227281
• Primes prime(k) such that prime(k) + 2*prime(k+1) and prime(k) + 2*prime(k+1) + 4*prime(k+2) are prime.at n=46A337213
• Prime numbersat n=2195