19305

Appears in sequences

• a(n) = (8*n+1)*(8*n+3)*(8*n+5)*(8*n+7).at n=1A001546
• n-phi-torial, or phi-torial of n: Product k, 1 <= k <= n, k relatively prime to n.at n=13A001783
• a(n) = Sum_{j=0..n} (n+j)*binomial(n+j,j).at n=6A002737
• a(n) = 3*binomial(2n-1,n).at n=7A003409
• a(n) = a(n-1) + 4*a(n-2), a(0) = a(1) = 1.at n=11A006131
• Odd numbers in the (1,2)-Pascal triangle A029635 that are different from 1.at n=57A029639
• Distinct odd numbers in the (1,2)-Pascal triangle A029635.at n=47A029642
• Central elements of the (1,2)-Pascal triangle A029635.at n=8A029651
• Distinct odd numbers in (2,1)-Pascal triangle A029653.at n=48A029660
• Dimensions of multiples of minimal representation of complex Lie algebra E6.at n=4A030648
• Longest edge a of smallest (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).at n=28A031173
• a(0) = 1; for n > 0, a(n) = binomial(n, floor(n/2)) + binomial(n-1, floor(n/2)).at n=16A050168
• a(n) = (2*n+7)!!/7!!, related to A001147 (odd double factorials).at n=4A051581
• A simple context-free grammar: convolution cube of A001002.at n=10A052703
• a(n) = binomial(n+7, 7)*(n+4)/4.at n=8A053347
• Numbers k such that the sum over the prime divisors of k equals the number of divisors of k.at n=42A069234
• Nonsquares with A072594(n) = 0.at n=34A072596
• a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, k-1) * 4^(k-1).at n=12A099580
• a(n) = 9*a(n-1) - 16*a(n-2), with a(0) = 1, a(1) = 9.at n=5A102902
• Numbers k such that 10^k + 6*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=15A102941