A137507 a(n) = 100^[n/10] + 2*n*10^[n/10]: inspired by Engel expansion of Pi.

1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 14000, 14200, 14400, 14600, 14800, 15000, 15200, 15400, 15600, 15800, 1060000, 1062000, 1064000, 1066000, 1068000, 1070000

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Mathematica

 Table[100^(Floor[n/10]) + 2*n*10^(Floor[n/10]), {n, 0, 50}] (* G. C. Greubel, Feb 23 2017 *)

Prog

(PARI) a(n) = (n+5 + 10^(floor((n+5)/10)))^2 - (n+5)^2; for (n=1, 30, print1(" "a(n)" ")) \\ changed n+5 to n. - M. F. Hasler, May 02 2008
(PARI) vector(30, n, n--; 2*n*10^(n\10) + 100^(n\10)) \\ M. F. Hasler, May 02 2008

Crossrefs

Cf. A006784.

Sequence in context: A352547 A014261 A066640 * A061808 A248608 A362680

Adjacent sequences: A137504 A137505 A137506 * A137508 A137509 A137510

Keyword

nonn

Author

Alexander R. Povolotsky, Apr 23 2008

Extensions

Edited by M. F. Hasler and N. J. A. Sloane, May 02 2008

Status

approved