20479

Properties

Appears in sequences

• Number of points of norm <= n in cubic lattice.at n=17A000605
• Primes that divide at least one term of Sylvester's sequence s = A000058: s(n+1) = s(n)^2 - s(n) + 1, s(0) = 2.at n=33A007996
• a(n) = 2*a(n-2) + 1.at n=24A010737
• Numerators of continued fraction convergents to sqrt(341).at n=7A041644
• Numbers having four 7's in base 8.at n=4A043452
• Primes of form 5*2^n-1.at n=4A050522
• a(n) = 5*2^(n-1) - 1, n>0, with a(0)=1.at n=13A052549
• Closed 3-dimensional ball numbers (version 1): a(n)= number of integer points (i,j,k) contained in a closed ball of diameter n, centered at (0,0,0).at n=34A053591
• a(n) = T(n,1), array T as in A054134.at n=13A054135
• Luhn primes: primes p such that p + (p reversed) is also a prime.at n=41A061783
• The table of permutations of N, each row induced by the rotation (to the right) of the n-th node in the infinite binary "decimal" fraction tree.at n=37A065658
• Permutation of N induced by rotating the node 2 right in the infinite planar binary tree shown at A065658.at n=7A065662
• Primes of the form 2^r*5^s - 1.at n=15A077313
• a(n) is the smallest x such that the quotient d(x+1)/d(x) equals n, where d = A000005.at n=12A080371
• Terms k of A002977 such that both (k-1)/2 and (k-1)/3 are also terms of A002977.at n=9A085249
• Smallest prime between 2^n and 2^(n+1), having a maximal number of 1's in binary representation.at n=13A091938
• Initial members of 25 consecutive primes in a 5 X 5 spiral wherein the mean of all 12 sums is prime.at n=36A094458
• Least p=prime(k) for which A118123(k)=n.at n=34A117877
• Numbers k such that tau(k) = tau(k+1) mod 691, where tau is Ramanujan's tau function A000594.at n=32A121733
• Prime numbers p such that p^3 - p + 1 and p^3 + p - 1 are both primes.at n=27A137463