18531
domain: N
Appears in sequences
- From a counter moving problem.at n=18A004138
- a(n) = Sum_{d|n} phi(d^4).at n=13A068970
- Number of ordered triples (i,j,k) with |i| + |j| + |k| <= n and gcd(i,j,k) <= 1.at n=25A100450
- Sum of the primes in ordered 3 X 3 prime squares.at n=34A105089
- Least k such that 2^(2^n)+k is prime.at n=18A129786
- Ulam's spiral (WNW spoke).at n=34A143859
- G.f. A(x) satisfies: A(x) = 1 / Product_{n>=1} (1 - x^n*A(x)^(n-1)).at n=11A210043
- Number of 3 X n 0..1 arrays with rows nondecreasing and antidiagonals unimodal.at n=28A224134
- a(n) = n*(7*n^2-12*n+7)/2.at n=18A226451