25377

Appears in sequences

• Least positive integer multiples of angle x such that their direction cosines form a unit vector: Sum_{k>0} cos(a(k)*x)^2 = 1, where a(1)=1 and x=2.at n=15A080137
• a(n) = Sum_{k = 0..floor(n/2)} floor(C(n-k,k)/(k+1)).at n=25A095719
• A modified Fibonacci sequence controlled by a toggle switch. The toggle switch (initial state of 2) flips between 2 and 3 after each reduction.at n=46A096016
• Least k such that k*6^n-1 , k*6^n+1, and 2*k*6^n-1 are prime; that is, twin primes and a Sophie Germain prime.at n=40A212481
• 50-gonal numbers: a(n) = 48*n*(n-1)/2 + n.at n=33A261343
• Exponential convolution of Catalan numbers and factorial numbers.at n=7A277176
• E.g.f.: exp( Integral exp(x^2) dx ).at n=9A279840
• Number of ways to choose a strict rooted partition of each part in a strict rooted partition of n.at n=27A301754
• a(n) = Sum_{k=1..n} sigma(n*k).at n=30A372710