26145

Appears in sequences

• Odd primitive abundant numbers.at n=35A006038
• Expansion of e.g.f.: exp(x^3/3 + x^2/2).at n=10A055814
• Odd primitive numbers such that n! divided by product of factorials of all proper divisors of n is not an integer.at n=34A075460
• 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=11A087415
• Odd admirable numbers: such that sigma(n) = 2n + 2d for some d | n.at n=7A109729
• Triangle read by rows: a(n,k) = number of partitions of an n-set into exactly k nonempty subsets, each of size <= 3.at n=49A111246
• Numbers k such that the digits of sigma(k) are a permutation of those of k, in base 10.at n=26A115920
• Triangle read by rows: T(n,k) is the number of partitions of [1, 2, ..., k] into exactly n blocks, each of size 1, 2 or 3 (n >= 0, 0 <= k <= 3n).at n=45A144385
• Triangle in A144385 with rows left-adjusted.at n=30A144399
• Triangle in A144385 read downwards by columns.at n=60A144402
• Triangle in A144385 read upwards by columns.at n=60A144417
• Irregular triangle of odd primitive abundant numbers (A006038) in which row n has numbers with n distinct prime factors.at n=34A188439
• Number of (w,x,y) with all terms in {0,...,n} and |w-x|+|x-y|+|y-w| <= w+x+y.at n=32A213487
• Unmatched value maps: number of n X n binary arrays indicating the locations of corresponding elements not equal to any horizontal, vertical or antidiagonal neighbor in a random 0..2 n X n array.at n=3A219099
• Unmatched value maps: number of nX4 binary arrays indicating the locations of corresponding elements not equal to any horizontal, vertical or antidiagonal neighbor in a random 0..2 nX4 array.at n=3A219102
• T(n,k)=Unmatched value maps: number of nXk binary arrays indicating the locations of corresponding elements not equal to any horizontal, vertical or antidiagonal neighbor in a random 0..2 nXk array.at n=24A219106
• 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=30A247317
• Irregular triangle read by rows where row n lists all odd primitive abundant numbers with n prime factors, counted with multiplicity.at n=34A287646
• Numbers n=2*k-1 where Sum_{j=1..k} (-1)^(j+1) * d(2*j-1) achieves a new record, with d(n) = number of divisors of n (A000005).at n=22A318737
• Odd recursive abundant numbers: odd numbers k such that A333926(k) > 2*k.at n=37A333950