20993

Appears in sequences

• a(n) = T(n,0) + T(n,1) + ... + T(n,[ n/2 ]), T given by A026703.at n=13A026711
• Numbers k such that k^2+k+2 is a palindrome.at n=23A027712
• Numbers k such that 69*2^k+1 is prime.at n=23A032384
• Least non-balanced x (i.e., not in A020492) such that sigma(p(n),x)/phi(x) is an integer, where p(n) = n-th prime.at n=27A078540
• The number of times a point sum n is attained in all 7^6 permutations of throwing 7 dice.at n=15A166322
• The number of times a point sum n is attained in all 7^6 permutations of throwing 7 dice.at n=20A166322
• Number of ways to arrange 4 nonattacking triangular rooks on an nXnXn triangular grid.at n=9A193982
• a(n) is the least k such that A261865(k) = A005117(n).at n=36A262036
• Squarefree semiprimes k such that k+1 is the product of three distinct primes and k+2 is the product of four distinct primes.at n=26A376352