A131812 Sum of all n-digit Woodall numbers.

8, 86, 1437, 6654, 81917, 827389, 17956860, 157286397, 1434451965, 12884901885, 114353504253, 1005022347261, 8761733283837, 166026255794172, 1337006139375613, 11434920928870397, 97390341941886973, 1799188051134513148, 14231374822490767357, 119903836479112085501

Offset

1,1

Links

Table of n, a(n) for n=1..20.

Eric Weisstein's World of Mathematics, Woodall Number.

Example

Sum of all 1-digit Woodall numbers is 1 + 7 = 8.
Sum of all 2-digit Woodall numbers is 23 + 63 = 86.
Sum of all 3-digit Woodall numbers is 159 + 383 + 895 = 1437.

Mathematica

digNum[n_] := Length @ IntegerDigits[n]; woodall[n_] := n * 2^n - 1; digCount = 0; sum = 0; cumsum = {}; Do[w = woodall[n]; If[digNum[w] > digCount, digCount++; AppendTo[cumsum, sum]]; sum += w, {n, 1, 65}]; Differences[cumsum] (* Amiram Eldar, Nov 30 2019 *)

Crossrefs

Cf. A003261.

Sequence in context: A268052 A268075 A202545 * A241259 A225314 A200767

Adjacent sequences: A131809 A131810 A131811 * A131813 A131814 A131815

Keyword

nonn,base,less

Author

Parthasarathy Nambi, Oct 23 2007

Extensions

More terms from Amiram Eldar, Nov 30 2019

Status

approved