26640

Appears in sequences

• a(1) = 0, a(2) = 0; for n > 2, a(n) - a(n-3) - a(n-5) - ... - a(n-p) = n if n is prime, otherwise = 0, where p = largest prime < n.at n=38A002123
• The number of permutations of n cards in which 4 will be the next hit after 2.at n=6A018932
• Number of identity bracelets with n labeled beads of 3 colors.at n=5A032338
• Every run of digits of n in base 3 has length 2.at n=32A033001
• Irrational unitary-phi amicable numbers: numbers a such that uphi(a) = uphi(b) = 2*(a^2-b^2)^(1/2) where uphi = A047994.at n=0A046710
• a(n) = (n^2 + 1)*n!.at n=6A082042
• a(0) = 1, a(n) = 20*sigma[3](n).at n=11A091983
• n times pi(n) is made of nontrivial runs of identical digits, where pi(n)=A000720(n).at n=10A116057
• Nonnegative values x of solutions (x, y) to the Diophantine equation x^2+(x+2401)^2 = y^2.at n=15A118630
• Number of permutations of floor(i*8/7), i=0..n-1, with all sums of 4 adjacent terms unique.at n=7A152345
• Numbers with prime factorization pqr^2s^4.at n=25A190107
• Molecular topological indices of the Moebius ladders.at n=19A192833
• a(n) = (n+1)*(n-2)*(n-3)/2.at n=37A212343
• The number of positive integer sequences of length n with no duplicate substrings of length greater than 1, every number different from its neighbors, and a minimal product (= A282169(n)).at n=16A284434
• Values of usigma(n) = usigma(n+1).at n=30A290303
• Values of bsigma(k) = bsigma(k+1), where bsigma is the sum of the bi-unitary divisors (A188999).at n=21A294029
• Number of 4-cycles in the n-polygon diagonal intersection graph.at n=34A300552
• Number of permutations pi of [n] such that s(pi) avoids the patterns 132 and 321, where s is West's stack-sorting map.at n=8A319028
• Sum of all the parts in the partitions of n into 9 squarefree parts.at n=40A326523
• Triangle read by rows: T(n,k) is the number of permutations of k elements from [1..n] in a circle with longest consecutive chain size less than 3, when 1 and n are considered to be consecutive, and rotations are considered to be distinct.at n=60A340108