21501

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 78 ones.at n=30A031846
• The smallest magic constant of an n X n magic square with distinct prime entries.at n=16A164843
• Numbers a = b + c where a, b, and c contain the same decimal digits.at n=29A203024
• Let G denote the 7-node, 12-edge graph formed from a hexagon with main diagonals drawn and a node at the center; a(n) = number of magic labelings of G with magic sum 2n.at n=8A244866
• Number of (n+1) X (6+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.at n=9A251147
• a(n) is the least exponent k greater than 1 such that prime(n)^k starts and ends in prime(n).at n=26A320775
• a(n) = n*2^10 - 3.at n=20A362361