9901009901

Appears in sequences

• Numbers, with an even number of digits, that are the sum of the squares of their two halves (leading zeros allowed only for the second half).at n=8A055616
• a(n) = A*10^(4*n+1)+B with A=99000*(10^(4*n)-1)/9999+10 and B=9900*(10^(4*n)-1)/9999+1.at n=0A055619
• Decimal numbers n such that after possibly prefixing leading 0's to n, the resulting number n' can be broken into 2 numbers of equal length, n' = xy, such that x^2+y^2 = n (y may also have leading zeros).at n=13A064942
• Positive integers of the form x*10^k + y which also equal x^2 + y^2 (x, y and k being positive integers).at n=16A275986