21797

Appears in sequences

• Expansion of (1-x)/(1 - x - x^3 - 2*x^4 + 2*x^5).at n=25A052914
• Numbers n such that sigma (phi ( n ) ) = sigma (sigma (n ) ) where phi is Euler's totient and sigma is the multiplicative sum-of-divisors function.at n=12A065556
• Number of fusenes with 24 hexagons, C_(2v) symmetry and containing n carbon atoms.at n=11A123606
• Composite numbers generated by the Euler polynomial x^2 + x + 41.at n=28A145292
• a(n) = (2^p - p^2 - 1)/6 where p = prime(n).at n=4A166743
• Semiprimes generated by the Euler polynomial x^2 + x + 41.at n=28A228183
• Number of (n+2)X(6+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3X3 column and antidiagonal sum not equal to 1 2 4 6 or 7.at n=1A252556
• T(n,k) = Number of (n+2) X (k+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 1 2 4 6 or 7.at n=22A252558
• Number of (2+2) X (n+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 1, 2, 4, 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 1, 2, 4, 6 or 7.at n=5A252560
• MM-numbers of crossing, capturing multiset partitions (with empty parts allowed).at n=7A326259
• Positions of 0's in A330314.at n=27A330325