21946

Appears in sequences

• Third row of Pascal-(1,4,1) array A081579.at n=42A081587
• a(n) = 997*n + 1009.at n=21A100776
• Number of lattice paths from (0,0) to (n,n) that do not go below the x-axis or above the diagonal x=y and consist of steps u=(1,1), U=(1,2), d=(1,-1), D=(1,-2) and H=(1,0).at n=11A230662
• Numbers n such that 2*n + prime(n) is a square.at n=40A256246
• Compound filter: a(n) = P(A055881(n), A278236(n)), where P(n,k) is sequence A000027 used as a pairing function.at n=32A286381
• Compound filter: a(n) = P(A257993(n), A278226(n)), where P(n,k) is sequence A000027 used as a pairing function.at n=38A286382
• Number of rooted self-avoiding king's walks on an infinite chessboard trapped after n moves.at n=3A323562