27613

Appears in sequences

• Expansion of g.f. Product_{k >= 1} (1 - x^k)^(-k*(k+1)/2).at n=13A000294
• Deceptive nonprimes: composite numbers k that divide the repunit R_{k-1}.at n=33A000864
• Strong pseudoprimes to base 32.at n=32A020258
• Strong pseudoprimes to base 55.at n=12A020281
• Strong pseudoprimes to base 74.at n=21A020300
• Downward vertical of triangular spiral in A051682.at n=39A081272
• a(n) = least semiprime with factors not previously used containing integers 2n and 2n+1 as substrings.at n=26A086887
• 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), (0, -1, 0), (0, 1, 0), (0, 1, 1), (1, 1, -1)}.at n=8A150409
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 286", based on the 5-celled von Neumann neighborhood.at n=42A271123
• Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 4 (mod m), where U(m) and V(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=4 and b=-1, respectively.at n=33A337627