18007

Appears in sequences

• a(n) = (d(n)-r(n))/2, where d = A026043 and r is the periodic sequence with fundamental period (1,1,0,0).at n=44A026044
• Numbers whose base-7 representation contains exactly four 3's.at n=30A043408
• Expansion of (1-x^3)/(1-x-x^2-x^3+x^5).at n=18A052972
• Number of isomers of polyhex hydrocarbons with C_(2v) symmetry with nineteen hexagons.at n=21A120448
• Smallest number k such that M(n)^2+k*M(n)-1 is prime with M(n)= Mersenne primes =A000668(n).at n=18A139426
• Duplicate of A139426.at n=18A143384
• 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, -1, -1), (-1, -1, 0), (-1, 0, -1), (-1, 1, 1), (1, 0, 0)}.at n=11A148066
• Positions of zeros in A165597.at n=29A165598
• In those partitions of n with every part >=3, the total number of parts (counted with multiplicity).at n=43A177739
• Number of nX3 0..2 arrays with no more than floor(nX3/2) elements unequal to at least one horizontal or vertical neighbor, with new values introduced in row major 0..2 order.at n=6A222583
• T(n,k)=Number of nXk 0..2 arrays with no more than floor(nXk/2) elements unequal to at least one horizontal or vertical neighbor, with new values introduced in row major 0..2 order.at n=38A222587
• T(n,k)=Number of nXk 0..2 arrays with no more than floor(nXk/2) elements unequal to at least one horizontal or vertical neighbor, with new values introduced in row major 0..2 order.at n=42A222587
• Smallest number k such that sopf(k)/digsum(k) = prime(n) where sopf(k) is the sum of the distinct primes dividing k and digsum(k) the sum of digits of k.at n=26A241049
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 398", based on the 5-celled von Neumann neighborhood.at n=40A271695
• G.f.: Sum_{k>=1} x^k/(1-x^k) * Product_{k>=1} (1+x^k).at n=39A305082
• a(n) = Sum_{-n<i<n, -n<j<n, gcd{i,j}=3} (n-|i|)*(n-|j|)/4.at n=31A331775