A092955 Starting at the integer 0, add one of each base-n digit in base n to a pile and then take from this pile the digits required to construct the current integer. Continue consecutively until reaching an integer, a(n), that requires digits not in the pile.

5, 13, 85, 183, 1729, 3932, 49153, 102790, 1600001, 3179144, 59719681, 114818732

Offset

2,1

Links

Table of n, a(n) for n=2..13.

Michael Brand, IBM Research "Ponder This" Challenge for April, 2004.

Formula

For even bases n > 4, the formula is a(n) := 2*n^(n-3) - 4*n^(n-4) + 1. No closed form is known for odd n.

Example

a(2)=5 because we first add 01 to the pile and then take 0 to make the integer 0. Next, we add another 01 to the pile (making it 011) and take the digit 1 to make the integer 1. Next we add 01 and take 10. Next we add 01 and take 11 (now the pile is just 00). Next we add 01 and take 100 (leaving just 0). Finally, we add 01 and now the pile is 001 but we need to form the number 101. So 101 (base 2) = 5 (base 10) is the first integer that cannot be formed.

Crossrefs

Sequence in context: A324418 A359316 A165262 * A190949 A263468 A350467

Adjacent sequences: A092952 A092953 A092954 * A092956 A092957 A092958

Keyword

base,nonn

Author

Michael Brundage, Apr 24 2004

Status

approved