A098727 Consider the sequence {b(n), n >= 1} of digits of the natural (or counting) numbers: 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0... (A007376); a(n) = b(n) + n.

2, 4, 6, 8, 10, 12, 14, 16, 18, 11, 11, 13, 14, 15, 17, 17, 20, 19, 23, 21, 26, 23, 29, 25, 32, 27, 35, 29, 38, 32, 31, 34, 34, 36, 37, 38, 40, 40, 43, 42, 46, 44, 49, 46, 52, 48, 55, 50, 58, 53, 51, 55, 54, 57, 57, 59, 60, 61, 63, 63, 66, 65, 69, 67, 72, 69, 75, 71, 78, 74, 71

Offset

1,1

Comments

Add each digit of the counting numbers to its rank.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

The sequence of digits of the counting numbers is
1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0...
The 15th term, for instance, is a 2. Thus 2+15=17 is the 15th term of this sequence.

Mathematica

Module[{dcn=Flatten[IntegerDigits/@Range[70]]}, Total/@Thread[ {dcn, Range[ Length[dcn]]}]] (* Harvey P. Dale, Mar 25 2022 *)

Crossrefs

Cf. A007376, A033307, A098728, A098729, A098732, A098733, A098734.

Sequence in context: A340479 A263042 A230099 * A182324 A095815 A063114

Adjacent sequences: A098724 A098725 A098726 * A098728 A098729 A098730

Keyword

base,easy,nonn

Author

Alexandre Wajnberg, Sep 30 2004

Extensions

More terms from Joshua Zucker, May 18 2006

Status

approved