18880

Appears in sequences

• Numbers n such that 8*3^n + 1 is prime.at n=17A005538
• Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite NES = NU-87 H4[Al4Si64O136].nH2O starting with a T6 atom.at n=13A019207
• a(n) = (2*n+1)*(11*n+1).at n=29A033575
• Sums of 4 distinct powers of 5.at n=29A038476
• Let f(x) = phi(x) + sigma(x); a(n) = least k such that at k begins a maximal run of length n of consecutive strict local extrema of f, or 0 if no such k exists.at n=33A066923
• Number of irreducible polynomials (over the rationals) of form a*x^2+b*x+c, 1 <= a,b,c <= n.at n=26A079671
• Number of symmetric singular n X n matrices over GF(2).at n=4A086879
• Triangle, read by rows, such that row n equals the inverse binomial transform of column n of the triangle A034870 of coefficients in successive powers of the trinomial (1+2*x+x^2), omitting leading zeros.at n=51A099605
• a(n) = n*(n+2)*(2*n-1)/3. Also, row sums of triangle A131422.at n=29A131423
• Duplicate of A131423.at n=29A143371
• Triangle read by rows: T(n,k) is the number of L-convex polyominoes of semiperimeter n, having k maximal rectangles (n >= 2, 1 <= k <= floor(n/2)). An L-convex polyomino is a convex polyomino in which any two cells can be connected by a path internal to the polyomino and which has at most 1 change of direction (i.e., one of the four orientations of the letter L). A maximal rectangle in an L-convex polyomino P is a rectangle included in P that is maximal with respect to inclusion.at n=28A181368
• Monotonic ordering of nonnegative differences 2^i-6^j, for 40>=i>=0, j>=0.at n=49A192116
• Monotonic ordering of nonnegative differences 4^i-6^j, for 40>= i>=0, j>=0.at n=26A192163
• Triangle of coefficients of polynomials u(n,x) jointly generated with A210754; see the Formula section.at n=51A210753
• Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^4<x^4+y^4.at n=30A211652
• Composites whose prime factorization in base 3 is an anagram of the number in base 3.at n=34A260047
• 40-gonal numbers: a(n) = 38*n*(n-1)/2 + n.at n=32A261191
• a(n) = 4*(n + 1)*(n + 2)*(4*n + 3)/3.at n=14A267522
• Expansion of Product_{k>=1} (1 + x^(2*k)) / (1 - x^k).at n=29A279328
• Expansion of the e.g.f. (1 - 2*x - 2*log(1 - x) - exp(2*x)*(1 - x)^2) / 4 - 1.at n=9A347210