19380

Appears in sequences

• Coefficients of Chebyshev polynomials.at n=15A005583
• Super ballot numbers: 60*(2n)!/(n!*(n+3)!).at n=11A007272
• a(n) = n*(n+1)*(n+2)*(n+3)/6.at n=17A033488
• Sums of 4 distinct powers of 5.at n=32A038476
• a(n) = LCM(binomial(n,0), ..., binomial(n,n)) / binomial(n,floor(n/2)).at n=41A048619
• 1 + Sum_{n>=1} a_n x^n = 1/Product_{n>=1} (1+x^n)^prime(n).at n=30A061151
• a(n) = lcm(1,2,...,2*n) / (n*binomial(2*n, n)).at n=20A068553
• Numbers k such that phi(k) = 2*tau(k)^2.at n=25A068564
• Numbers k such that k-1, k+1 and k^2+1 are prime numbers.at n=37A070155
• Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.at n=5A070156
• Numbers k such that k-1, k+1, k^2+1, k^4+1 and k^8+1 are all prime numbers.at n=1A070157
• Numbers k such that the sign of core(k)-phi(k) is not equal to 2*mu(k)^2-1, where core(k) is the squarefree part of k.at n=35A070237
• Numbers k such that k+1, k^2+1 and k^4+1 are primes.at n=42A070325
• Numbers k such that k+1, k^2+1, k^4+1 and k^8+1 are primes.at n=3A070655
• Integers k such that omega(k) = omega(k-1) + omega(k-2) + omega(k-3), where omega(n) is the number of distinct prime factors of n.at n=12A076252
• In the following triangle the n-th row contains n n-digit (or (n-1)-digit) numbers whose concatenation (with a 0 prefixed for (n-1)-digit numbers) gives a substring of the cyclic concatenation of 1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,...: 1; 12 34; 123 456 789; 1234 5678 9012 3456; 12345 67890 12345 67890 12345; ... Sequence contains the sum of the terms of a row.at n=3A078195
• Numbers k such that sopfr(k)=tau(k).at n=34A078511
• Sum of lists created by n substitutions k -> Range[k+1,0,-2] starting with {0}, counting down from k+1 to 0 step -2.at n=13A084081
• Numbers whose number of divisors equals the sum of their separate prime-power decompositions.at n=9A087004
• Normalized triangle of odd numbered entries of even numbered rows of Pascal's triangle A007318.at n=48A091043