20320

Appears in sequences

• Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite EPI = Epistilbite Ca3[Al6Si18O48].16H2O starting with a T3 atom.at n=13A019117
• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 71.at n=29A031569
• Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 2,0,3.at n=4A037624
• Numbers n such that 117*2^n-1 is prime.at n=40A050584
• Nonprime numbers k such that k | sigma_3(k) + phi(k)^3.at n=16A055970
• Numbers k such that sigma(k) = phi(k*bigomega(k)).at n=9A068400
• Numbers which are sums of two, three and four cubes.at n=25A085337
• Numbers which are sums of two, three, four and also sums of five cubes.at n=24A085338
• Numbers n such that sigma(n) = 6*phi(n).at n=8A104900
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 1), (0, 0, 1), (0, 1, -1), (1, -1, 0)}.at n=11A148097
• 28-gonal numbers: a(n) = n*(13*n - 12).at n=40A161935
• Row sums of A163357 and A163359.at n=30A163365
• Expansion of 1/((1 +x +x^2)^2 *(1 +x^2 +x^3)^3).at n=33A167177
• Numbers k such that phi(phi(k)) = sigma(rad(k)).at n=30A173748
• Sums of least knight's moves from (0,0) to points in the square lattice [-n,n]x[-n,n].at n=23A183047
• Left edge of the triangle in A033291.at n=39A192735
• Number of -n..n arrays x(0..3) of 4 elements with zero sum and no two or three adjacent elements summing to zero.at n=15A200431
• Triangle of coefficients of polynomials v(n,x) jointly generated with A210747; see the Formula section.at n=40A210748
• a(n) = sum of all divisors of all positive integers <= prime(n).at n=36A244583
• Numbers n such that 36n+11, 36(n+1)+11, 36(n+2)+11 and 36(n+3)+11 are prime.at n=20A255608