20280

Appears in sequences

• Number of partitions of n with equal number of parts congruent to each of 0 and 2 (mod 4).at n=48A035541
• Numbers k such that k | (sigma(k) - d(k) - phi(k)) and k is not a prime or twice a prime.at n=3A055971
• Numbers k that, when expressed in base 5 and then interpreted in base 8, give a multiple of k.at n=38A062930
• Sum_{i for which n - i*(i-1)/2 >= 0} binomial (n - i*(i-1)/2, i).at n=28A063978
• Sum of three solutions of the Diophantine equation x^2 - y^2 = z^3.at n=13A085409
• Unitary sigma-unitary phi super perfect numbers: USUP(USUP(n))= n/k for some integer k.at n=37A093863
• Even triangle n!. This table read by rows gives the coefficients of sum formulas of n-th factorials (A000142). The k-th row (6>=k>=1) contains T(i,k) for i=1 to k+3, where k=[2*n+1+(-1)^(n-1)]/4 and T(i,k) satisfies n! = Sum_{i=1..k+3} T(i,k) * n^(i-1) / (2*k-2)!.at n=9A102409
• a(1)=11, If a(n-1)=abcde..., where a,b,c,d,e... are the digits, then a(n)=abcde...+a*bcde...+ab*cde...+abc*de...+abcd*e...+....at n=17A108722
• Elements of A065607 from primitive triples.at n=21A120693
• G.f.: (x^2+6*x^3+7*x^4+8*x^5+4*x^6-3*x^8-2*x^9-x^10) / ((1-x)^2*(1-x^2)^3*(1-x^3)^4*(1-x^4)).at n=14A127813
• The count of how many queens must be placed tentatively onto a board while seeking a first solution to the "N-Queens on an N x N chessboard" puzzle.at n=14A140450
• Numbers that are divisible by the product of the digit-sums of their neighbors.at n=31A152826
• Primitive numbers in A158235.at n=24A158245
• Primitive numbers n whose square can be represented as a four "digit" repdigit number in some base < n.at n=3A158912
• Erroneous duplicate version of A181496.at n=10A165146
• a(n) = 13*n*(n+1).at n=39A173307
• Total Wiener index of double-star trees with n nodes.at n=30A186235
• Right edge of the triangle in A033291.at n=38A192736
• a(n) = Sum_{0<j<n} n^3-j^3.at n=11A206808
• Areas A of the triangles such that A, the sides and the three altitudes are integers.at n=26A210643