19641

Appears in sequences

• One seventh of the sum of the first n primes, when an integer.at n=31A112272
• Number of permutations of length n which avoid the patterns 1234, 2143, 3421.at n=25A116842
• Number of planar n X n X n binary triangular grids with no more than 4 ones in any 3 X 3 X 3 subtriangle.at n=5A153525
• Number of ways to place two non-attacking queens on all free n-ominoes.at n=8A171009
• Number of nX2 0..2 arrays with the row and column sums nondecreasing.at n=6A203324
• Number of nX7 0..2 arrays with the row and column sums nondecreasing.at n=1A203329
• T(n,k)=Number of nXk 0..2 arrays with the row and column sums nondecreasing.at n=29A203330
• T(n,k)=Number of nXk 0..2 arrays with the row and column sums nondecreasing.at n=34A203330
• [s(k)-s(j)]/10, where the pairs (k,j) are given by A205877 and A205878, and s(k) denotes the (k+1)-st Fibonacci number.at n=28A205880
• Consider any concatenation of the type n = concat(a,b). Sequence lists numbers that are the sum of the products of some of such couples a and b.at n=30A265737
• Least k > 1 such that phi(k*n-1) = phi(k*n+1), or -1 if no such k exists.at n=19A276052
• Least k such that phi(k*n-1) = phi(k*n+1), or -1 if no such k exists.at n=19A276373