30840

Appears in sequences

• Numbers k such that 105*2^k+1 is prime.at n=47A032402
• Periodic vertical binary vectors computed for powers of 3: a(n) = Sum_{k=0 .. (2^n)-1} (floor((3^k)/(2^n)) mod 2) * 2^k.at n=4A037096
• Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,3,2,0.at n=7A037709
• Number of orientable necklaces with 2n beads and two colors which when turned over produce their own color complement.at n=17A059078
• Triangle read by rows: a(n,m) = T[n,m,m] where T[i,j,k] is the 3-dimensional pyramid defined by T[n,m,0]=1 and T[i,j,k]=0 if j>i or k>j and T[i,j,k]=T[i-1,j,k]+T[i,j-1,k]+T[i,j,k-1].at n=49A065078
• Solutions to phi(gpf(x)) - gpf(phi(x)) = 254 = c are special multiples of 257, x = 257k, where largest prime factors of factor k were observed from {2, 3, 5, 17}. See solutions to other even cases of c (=A070813): A007283 for 0, A070004 for 2, A070814 for 14, A070816 for 65534.at n=27A070815
• a(1)=1, a(n) is the smallest integer > a(n-1) such that the sum of elements of the simple continued fraction for S(n)=1/a(1)+1/a(2)+...+1/a(n) equals n*(n+1)/2 the n-th triangular number.at n=31A071184
• a(n) = n*(n - 1)*(n^2 + 1)/2.at n=16A071252
• List of codewords in binary lexicode with Hamming distance 7 written as decimal numbers.at n=29A075937
• Sum of largest parts of all partitions of n into odd parts.at n=44A092322
• Number of compositions of n such that each part is adjacent to an equal part.at n=28A114901
• Integers i such that 9*i = 25 X i, but 17*i is not 49 X i.at n=33A115811
• Triangle read by rows: expansion of p(x,n)=If[n == 0, 1, (x + 1)^n + 2^(n - 3)*Sum[Binomial[n, m]*x^m*(1 + x^(n - 2*m)), {m, 1, n - 1}]].at n=58A146767
• Numbers n with property that n+41, n^2+41 and n^3+41 are all primes.at n=17A175260
• a(n+1) = 2*a(n) + A014017(n+5), a(0) = 0.at n=19A191497
• Numbers a(n) with property a(n) + a(n+4) = 2^(n+4) - 1 = A000225(n+4).at n=15A224520
• Numbers k such that k is the average of four consecutive primes k-11, k-1, k+1 and k+11.at n=28A259025
• Expansion of 1/(1 - Sum_{k>=1} x^p(k)), where p(k) is the number of partitions of k (A000041).at n=17A280254
• Number of edges in regular n-gon after 2 generations of mitosis.at n=17A349968