258048

Appears in sequences

• Number of noninvertible 2 X 2 matrices over Z/nZ (determinant is a divisor of 0).at n=22A020479
• Theta series of (putative) extremal 2-modular even lattice in dimension 24.at n=3A034600
• Triangle whose (i,j)-th entry is binomial(i,j)*4^(i-j)*9^j.at n=29A038239
• Triangle whose (i,j)-th entry is binomial(i,j)*9^(i-j)*4^j.at n=34A038294
• 6-fold convolution of A000302 (powers of 4); expansion of 1/(1-4*x)^6.at n=5A045543
• a(n) = T(2n,n), where T is given by A048113.at n=11A048116
• a(n) = 4^n * (2^n - 1).at n=6A059409
• Number of walks of length n on square lattice, starting at origin, staying on points with x+y >= 0.at n=10A060899
• Numbers k such that phi(prime(k) + 1) == 0 (mod k).at n=26A067732
• Jordan function J_6(n).at n=7A069091
• 15-almost primes (generalization of semiprimes).at n=14A069276
• Triangular array T(n,k) read by rows, giving number of labeled free trees such that the root is smaller than all its children, with respect to the number n of vertices and to the degree k of the root.at n=31A071210
• Triangle, read by rows, of coefficients for the third iteration of the hyperbinomial transform.at n=30A089463
• a(n) = 4^n*(2*n)!/(n!)^2.at n=5A098430
• Expansion of e.g.f. BesselI(0,4*x)+BesselI(1,4*x)/2.at n=10A098664
• a(n) = n-th n-almost prime.at n=14A101695
• Triangle T, read by rows, where matrix power T^-2 has -2^(n+1) in the secondary diagonal: [T^-2](n+1,n) = -2^(n+1), with all 1's in the main diagonal and zeros elsewhere.at n=22A117265
• Number of subsets of {1,2,...,n} which contain no three consecutive odd numbers.at n=18A127195
• a(n) = n^6 - n^4.at n=8A136038
• T(i,j) = (-1)^(i+j)*(i+1)*binomial(i,j)*2^(i-j)*4^j.at n=38A137337