121201

Appears in sequences

• Any digit "d" (except the first two) is the absolute difference between x and y -> x=sum of the 2 digits standing immediately to the left of "d", y=sum of the 2 digits standing immediately to the right of "d".at n=8A102355
• Least number k not divisible by 10 such that k^n contains n zeros.at n=39A241495
• a(n) is the least number k not ending in 0 such that k^n has at least n 0's in its decimal expansion.at n=39A368397
• a(n) = n^4 - 4*(n^3-n)/3.at n=19A389090