21648

Appears in sequences

• arctan(arcsin(arcsin(x)))=x+12/5!*x^5+248/7!*x^7+21648/9!*x^9...at n=4A012066
• Schoenheim bound L_1(n,8,7).at n=14A036835
• a(n) = A045820(n)/2.at n=17A045822
• Composite numbers k such that phi(k) divides sigma(k) - 2*k.at n=22A068412
• Indices of primes in sequence defined by A(0) = 47, A(n) = 10*A(n-1) - 43 for n > 0.at n=11A101721
• Averages of twin prime pairs which can be represented as a sum of three consecutive of such pair averages.at n=23A160917
• Terms in A177950 that are not in A002778.at n=42A175440
• 41 times triangular numbers.at n=32A195038
• Nonnegative values x of solutions (x, y) to the Diophantine equation x^2 + (x+84847)^2 = y^2.at n=14A201917
• Averages q of twin prime pairs, such that q concatenated to q is also the average of a twin prime pair.at n=27A235109
• Number of length n+5 0..3 arrays with no six consecutive terms having two times the sum of any two elements equal to the sum of the remaining four.at n=2A249228
• T(n,k)=Number of length n+5 0..k arrays with no six consecutive terms having two times the sum of any two elements equal to the sum of the remaining four.at n=12A249233
• Number of length 3+5 0..n arrays with no six consecutive terms having two times the sum of any two elements equal to the sum of the remaining four.at n=2A249236
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n) - 1, where a(0) = 2, a(1) = 3, b(0) = 1, b(1) = 4, b(2) = 5, and (a(n)) and (b(n)) are increasing complementary sequences.at n=17A295965
• Numbers k such that sigma(k) = 2*k + 3*phi(k).at n=4A392691