20411

Properties

Appears in sequences

• Smallest prime p==3 (mod 8) such that Q(sqrt(-p)) has class number 2n+1.at n=39A002148
• a(n) = n^3 + n^2 - 1.at n=26A003777
• Primes that remain prime through 3 iterations of function f(x) = 5x + 4.at n=29A023284
• Number of partitions of n that do not contain 8 as a part.at n=38A027342
• Number of partitions of n with equal number of parts congruent to each of 2 and 3 (mod 5).at n=48A035559
• Numbers p from A001125 such that 2*p-3 is prime.at n=28A063939
• Numbers k such that k, sigma(k) and phi(k) have the same decimal digits (ignoring multiplicity).at n=25A082059
• Primes of the form 4*k-1 such that 8*k-1 and 16*k-1 are also primes.at n=31A101791
• Least j > 1 for n > 0 such that j^2 = (n^2 + 1)*(k^2) + (n^2 + 1)*k + 1 where k sequence = A106230.at n=27A106229
• Primes p such that 2p+1, 4p+3, 6p+5 are all primes.at n=20A107020
• Numbers n such that the last 9 decimal digits of the n-th Fibonacci number is pandigital 1-9.at n=6A112371
• Triangle, read by rows, where row n forms a polynomial in y=2*k that generates diagonal n as k=0,1,2,... for n>=0; thus T(n,k) = Sum_{j=0..n-k} T(n-k,j)*(2*k)^j, with T(n,0)=T(n,n)=1.at n=50A113711
• Primes congruent to 37 mod 61.at n=38A142835
• Primes congruent to 34 mod 71.at n=33A154624
• a(n) = 729*n - 1.at n=27A158395
• a(n) = 28*n^2 - 1.at n=26A158554
• Fajtlowicz p-primes.at n=32A185955
• Number of nX4 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,3,1,1,0 for x=0,1,2,3,4.at n=6A197499
• Number of nX7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,3,1,1,0 for x=0,1,2,3,4.at n=3A197502
• T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,3,1,1,0 for x=0,1,2,3,4.at n=48A197503