A083813 a(n) = 3*(10^n-1).

27, 297, 2997, 29997, 299997, 2999997, 29999997, 299999997, 2999999997, 29999999997, 299999999997, 2999999999997, 29999999999997, 299999999999997

Offset: 1

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003

Keywords

• nonn

Comments

Original definition: 3n+1 is the digit reversal of n+1.

1. a(n) = 27 + 270 + 2700 + ... up to n terms = sum of n terms of the geometric progression with the first term 27 and common ratio 10.

2. a(n) = 27*A000042(n) (the unary sequence).

Equals A086574 restricted to positive indices. See that entry for many more comments, formulas and references. - M. F. Hasler, Jul 29 2016

Crossrefs

Essentially a duplicate of A086574.

Cf. A000042, A083811, A083812.

Programs

Mathematica

3(10^Range[20]-1) (* or *) Table[10 FromDigits[PadRight[{2},n,9]]+7,{n,20}] (* Harvey P. Dale, Jan 25 2020 *)

Extensions

Edited by M. F. Hasler, Jul 29 2016