20723

Appears in sequences

• For n>0, a(n) is the least quasi-Carmichael number to base n; a(0) = least composite squarefree integer.at n=14A029590
• Numerators of continued fraction convergents to sqrt(926).at n=5A042790
• a(n) is the smallest k such that (k^4 + 1)/(n^4 + 1) is an integer > 1.at n=39A066018
• a(n) = n^4 - n - 1.at n=11A126423
• 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=12A148007
• Least k such that the sum of the semiprime divisors equals n times the sum of the prime divisors, or 0 if no such k exists.at n=25A227419
• Number of partitions p of n such that (number of distinct parts of p) <= max(p) - min(p).at n=37A239955
• Number of power series 1 + c_1*x^1 + c_2*x^2 + ... + c_{n-1}*x^{n-1} + O(x^n) with c_k in {-1, 0, 1} whose reciprocal has the same property.at n=14A244629
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 593", based on the 5-celled von Neumann neighborhood.at n=27A273121
• a(n) = (n-4)*(n+1)*(n+3)/6.at n=46A275874
• Number of maximal matchings in the n-prism graph.at n=12A284703
• Numbers of the form HMMSS with primes H < 24 and MM, SS < 60, for which the number of seconds after midnight, 3600*H+60*MM+SS, is also prime.at n=17A295011
• a(n) = Sum_{k=1..n} k^floor(n/k).at n=24A345100
• Coefficient of x^n in the expansion of 1 / ( (1-x) * (1-x-x^2)^2 )^n.at n=5A372458