28035

Appears in sequences

• Odd primitive abundant numbers.at n=37A006038
• a(n) = Sum_{k >= 1} floor(3*tau^(n-k)).at n=17A020958
• Sum of the prime factors of k equals half the sum of the prime factors of k + 1.at n=17A074213
• Odd numbers k such that abs(sigma(k)-2k) <= sqrt(k). Abundance-radius = abs(sigma(k)-2k) does not exceed square root of k and k is odd.at n=13A087415
• Odd admirable numbers: such that sigma(n) = 2n + 2d for some d | n.at n=8A109729
• Irregular triangle of odd primitive abundant numbers (A006038) in which row n has numbers with n distinct prime factors.at n=35A188439
• Triangle read by rows: T(n,k) (1 <= k <= n-1, n >= 2) = d(2*(n-k)-1)*(d(2*n-2)/d(2*(n-k)-2) - d(2*n-3)/d(2*(n-k)-3)), where d = A006882 is the double factorial function.at n=17A202212
• Numbers x such that the sum of all their cyclic permutations is equal to that of all cyclic permutations of sigma(x) and all cyclic permutations of Euler totient function phi(x).at n=34A247317
• G.f. A(x) satisfies: 1+x = A(x)^2 + A(x)^4 - A(x)^5.at n=6A249926
• Numbers divisible by prime(d) for each digit d in their base-6 representation, none of which may be zero.at n=46A256876
• Irregular triangle read by rows where row n lists all odd primitive abundant numbers with n prime factors, counted with multiplicity.at n=36A287646
• O.g.f. A(x) satisfies: A(x) = 1 + Integral (x/A(x)^4)' / (x/A(x)^7)' dx.at n=6A303064
• Integers k such that A014841(k) = A014841(k+1).at n=8A356961
• a(n) is the number of sets of distinct four-cuboid combinations that fill an n X n X n cube excluding combinations that contain cube-shaped cuboids.at n=30A386756
• Odd numbers k for which A003961(k) > 2*k and A003961(k)-2*k OR A003961(k)-sigma(k) = A003961(k)-2*k, where OR is bitwise-or (A003986) and A003961 is fully multiplicative with a(p) = nextprime(p).at n=5A388029
• Primitive terms of A388028.at n=49A388030
• Primitive terms of A388034.at n=50A388035
• Odd numbers k such that gcd(A276086(sigma(k)-k), A276086(k)) is equal to A276086(k), where A276086 is the primorial base exp-function, and sigma is the sum of divisors function.at n=18A388267
• Numbers k with abundance 90: sigma(k) - 2*k = 90.at n=2A389703