18650

Appears in sequences

• From George Gilbert's marks problem: jumping 4 marks at a time (initial positions).at n=19A019595
• Sum of first prime(n) primes.at n=23A022094
• Integer part of ((4th elementary symmetric function of 2,3,...,n+4)/(2nd elementary symmetric function of 2,3,...,n+4)).at n=27A024181
• a(n) = (d(n)-r(n))/2, where d = A026046 and r is the periodic sequence with fundamental period (0,1,0,1).at n=44A026047
• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 8.at n=37A031421
• McKay-Thompson series of class 34a for the Monster group.at n=42A058639
• Expansion of 1/(1+2*x^2-x^3).at n=32A077965
• Expansion of 1/(1+2*x^2+x^3).at n=32A077967
• Least x = a(n) such that sum of common prime divisors (without multiplicity) of sigma(x) and phi(x) equals n, or 0 if such number (apparently) does not exist.at n=35A082056
• Numbers k such that the square of k contains sigma(k) as a substring, in base 10.at n=11A113654
• Sum of the first F(n) primes, where F(n) is the n-th Fibonacci number.at n=11A117400
• 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, 0), (0, 1, -1), (0, 1, 0), (1, 0, 1), (1, 1, 0)}.at n=7A151134
• Number of excursions of length n with Motzkin-steps avoiding the consecutive steps UU, HH, DU and DD.at n=27A329690
• The sum S of the maximum number of consecutive primes starting with 2 such that S <= prime(n)^2.at n=32A346134
• Fixed points in A360519.at n=10A361105
• Total number of "block reversals" needed to transform all permutations of [n] into 12...n.at n=7A380576