A099674 Partial sums of repdigits of A002281.

7, 84, 861, 8638, 86415, 864192, 8641969, 86419746, 864197523, 8641975300, 86419753077, 864197530854, 8641975308631, 86419753086408, 864197530864185, 8641975308641962, 86419753086419739, 864197530864197516

Offset

1,1

Links

Table of n, a(n) for n=1..18.

Formula

a(n) = (7/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004

Example

7 + 77 + 777 + 7777 + 77777 = a(5) = 86415.

Mathematica

<<NumberTheory`NumberTheoryFunctions` Table[{k, Table[Apply[Plus, Table[k*(10^n-1)/9, {n, 1, m}]], {m, 1, 35}]}, {k, 1, 9}]
Table[8/9*Sum[10^i - 1, {i, n}], {n, 18}] (* Robert G. Wilson v, Nov 20 2004 *)

Crossrefs

Cf. A057932, A002275-A002283, A099669-A099675.

Sequence in context: A269895 A272496 A177009 * A067413 A370779 A166178

Adjacent sequences: A099671 A099672 A099673 * A099675 A099676 A099677

Keyword

base,nonn

Author

Labos Elemer, Nov 17 2004

Status

approved