27715
domain: N
Appears in sequences
- a(n) = p(1)p(n) + p(2)p(n-1) + ... + p(k)p(n+1-k), where k = [ (n+1)/2 ], p = A000040 = the primes.at n=30A024697
- Number of base 27 circular n-digit numbers with adjacent digits differing by 1 or less.at n=8A124726
- Consider all consecutive integer Pythagorean 11-tuples (X, X+1, X+2, X+3, X+4, X+5, Z-4, Z-3, Z-2, Z-1, Z) ordered by increasing Z; sequence gives X values.at n=3A157096
- Main diagonal of Ludic array A255127 (and A255129): a(n) = A255127(n,n).at n=27A255410
- Expansion of (1-2*x)/((2-x)*sqrt(5*x^2-6*x+1))+1/(2-x).at n=8A262664
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 123", based on the 5-celled von Neumann neighborhood.at n=34A270212
- a(n) = Sum_{k=0..n} (-1)^k*floor((1 + sqrt(2))^k).at n=12A277789
- Array read by antidiagonals: T(n,k) is the number of unrooted 3-connected triangulations of a disk with n interior nodes and k nodes on the boundary, n >= 1, k >= 3.at n=42A342053
- Number of unrooted 3-connected triangulations of a pentagon with n interior nodes.at n=6A342054