19004

Appears in sequences

• Numbers k such that 13*4^k + 1 is prime.at n=11A002257
• Numbers k such that sigma(k+2) = sigma(k).at n=25A007373
• Numbers n such that 243*2^n-1 is prime.at n=42A050880
• Numbers k such that sigma(k-2) + sigma(k+2) = sigma(2k).at n=10A067172
• Molien series for symmetrized weight enumerators of self-dual codes over GF(4) + GF(4)u with u^2 = 0.at n=43A092549
• Number of permutations of length n which are contained in a pin sequence.at n=7A138619
• Sum_{0<j<k<=n} P(k)-P(j), where P(j)=A065091(j) is the j-th odd prime.at n=28A206803
• Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with set{t,u,v in 0,1}((x[i+t]+x[j+u]+x[k+v])*(-1)^(t+u+v)) having two, three, four, six or seven distinct values for every i,j,k<=n.at n=7A211583
• a(n) = Sum_{i=1..n} (-1)^{i+1} prime(i)^2, where prime(k) denotes the k-th prime: alternating sum of the squares of the first n primes.at n=40A240860
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 590", based on the 5-celled von Neumann neighborhood.at n=39A273117
• Anagrasum integers: integers N that exactly reproduce their set of digits when we form the set of sums of pairs of adjacent digits.at n=39A296521
• a(n) = 54*n^2 - 26*n + 4 (n>=1).at n=18A304381
• Number of compositions (ordered partitions) of n into distinct parts that do not divide n.at n=39A332001
• For 1<=x<=n, 1<=y<=n, write gcd(x,y) = u*x+v*y with u,v minimal; a(n) = n^4*s, where s is the population variance of the values of u.at n=9A345687
• Numbers that can be represented as p^r + q^s with 4 distinct odd primes p, q, r, s.at n=1A390179