18980

Appears in sequences

• a(n) = Sum_{d|n, n/d=1 mod 4} d^3 - Sum_{d|n, n/d=3 mod 4} d^3.at n=26A050471
• a(n) = (1/6)*(2*n - 3)*(n + 2)*(n + 1).at n=40A058373
• a(n) = n^3 - n^2 + n - 1 = (n-1) * (n^2 + 1).at n=27A062158
• Numbers k such that reverse(gpf(k)) = gpf(k+1), where gpf(n) = A006530(n); a(1)=1.at n=27A071844
• Named periods in the Mayan/Mesoamerican calendars.at n=6A081244
• Given the infinite continued fraction (1+i)+((1+i)/(1+i)+((1+i)/((1+i)+...)))), where i is the square root of (-1), this is the denominator of the convergents.at n=11A093727
• Number of partitions of n such that the least part occurs exactly five times.at n=50A097093
• a(n) = 3*a(n-1) - a(n-3) + 3*a(n-4), with initial values 0,0,0,1.at n=12A133405
• Numbers k such that 12^k + 7 is prime.at n=18A137653
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (1, -1, 1), (1, 0, 1), (1, 1, -1), (1, 1, 1)}.at n=7A151004
• a(n) = 1000*n - 20.at n=18A157515
• Coefficient of x in the reduction by x^2 -> x+1 of the polynomial p(n,x) defined at Comments.at n=17A192982
• Triangle by rows relating to A081696.at n=46A204842
• Number of nX5 0..1 arrays with rows, diagonals and antidiagonals unimodal.at n=3A223666
• T(n,k)=Number of nXk 0..1 arrays with rows, diagonals and antidiagonals unimodal.at n=31A223669
• Number of 4Xn 0..1 arrays with rows, diagonals and antidiagonals unimodal.at n=4A223671
• Real part of Sum_{k=0..n} (k + i^k)^2, where i=sqrt(-1).at n=38A236377
• Total number of parts in all overcompositions of n.at n=10A236625
• Expansion of triangle T(n,k) of p-adic valuations of A052129(n) (Somos' quadratic recurrence sequence).at n=63A239148
• Number of tilings of a 5 X 2n rectangle using 2n pentominoes of shape P.at n=9A247076