39689

Appears in sequences

• Numerators of continued fraction convergents to sqrt(205).at n=7A041380
• Numerators of continued fraction convergents to sqrt(820).at n=11A042582
• Numbers k such that phi(k) + phi(k+1) = sigma(k).at n=14A067799
• Nonprime numbers n such that phi(n) divides n^2 - 1, where phi(n) (A000010) is Euler's totient function.at n=19A098271
• a(n) = 4*n^3 - 6*n^2 + 1.at n=22A141530
• 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, 0), (0, 1, -1), (1, 0, 1), (1, 1, -1)}.at n=10A148724
• a(n) = (n+3)^2*n/2 + 1.at n=41A154560
• Number of nX5 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,1,3,4 for x=0,1,2,3,4.at n=11A195975
• Lucas pseudoprimes.at n=31A217120
• Number of (n+2)X(3+2) 0..3 arrays with every 3X3 subblock row and column sum not equal to 0 2 4 6 or 7 and every 3X3 diagonal and antidiagonal sum equal to 0 2 4 6 or 7.at n=6A252518
• Number of (n+2)X(7+2) 0..3 arrays with every 3X3 subblock row and column sum not equal to 0 2 4 6 or 7 and every 3X3 diagonal and antidiagonal sum equal to 0 2 4 6 or 7.at n=2A252522
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum not equal to 0 2 4 6 or 7 and every 3X3 diagonal and antidiagonal sum equal to 0 2 4 6 or 7.at n=38A252523
• Squarefree composite numbers n such that p^2 - 1 divides n^2 - 1 for every prime p dividing n.at n=1A287119
• Composite squarefree numbers k such that k^2-1 is divisible by p-1 and p+1, where p are all the prime factors of k.at n=6A306685
• Sum of the odd parts in the partitions of n into 5 parts.at n=45A309545
• Numbers k such that k divides A306069(k).at n=7A344731