21201

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 FER = Ferrierite Na2Mg2[Al6Si30O72].18H2O starting with a T3 atom.at n=13A019131
• n written in fractional base 3/2.at n=19A024629
• Number of ways of numbering the faces of a cube with nonnegative integers so that the sum of the 6 numbers is n.at n=33A054473
• a(0) = 0, a(n) = smallest composite k such that phi(k + 2^n) = phi(k) + 2^n; also cototient(k + 2^n) = cototient(k).at n=14A063104
• 4-Smith numbers.at n=24A103125
• Binomial transform of n^n (with interpolated zeros).at n=10A110140
• 11^n+9^n-1^n.at n=4A155670
• Number of zero-sum -n..n arrays of 4 elements with first and second differences also in -n..n.at n=26A201875
• Indices of heptagonal numbers that are also decagonal.at n=3A203409
• Partial sums of A255744.at n=24A255765
• Numbers k such that the decimal number concat(4,k) is a square.at n=38A273359
• Numbers with digits in {0,1,2} such that every other digit is strictly less than its neighbors.at n=29A306105
• a(n)/A002939(n+1) is the Kirchhoff index of the join of the disjoint union of two complete graphs on n vertices with the empty graph on n+1 vertices.at n=10A338109