A080463 Sum of the two numbers formed by alternate digits of n.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 8, 9, 10, 11, 12, 13, 14, 15, 16

Offset

0,3

Comments

First 99 terms match with those of A007953.

They also match A209685. - M. F. Hasler, Jan 10 2016

Links

M. F. Hasler, Table of n, a(n) for n = 0..10000

Formula

From Robert Israel, Jan 10 2016: (Start)

f(n) = n mod 10 + floor(n/10) mod 10 + 10*f(floor(n/100)).

G.f. G(x) satisfies G(x) = (x + 2x^2 + ... + 9x^9)/(1-x^10) + (x^10 + 2 x^20 + ... + 9 x^90)/((1-x)(1+x^10+...+x^90) + 10 (1 + x + ... + x^99) G(x^10).

(End)

Example

a(132546) = 124 + 356 = 480.

Maple

f:= proc(n) option remember; n mod 10 + (floor(n/10) mod 10) + 10*procname(floor(n/100)) end proc:
f(0):= 0:
seq(f(n), n=0..1000); # Robert Israel, Jan 10 2016

Prog

(PARI) A080463(n)=abs(vector(#n=digits(n), j, 10^((#n-j)\2))*n~) \\ M. F. Hasler, Jan 10 2016

Crossrefs

Cf. A007953, A080464, A080465.

Sequence in context: A033930 A076314 A007953 * A209685 A114570 A349194

Adjacent sequences: A080460 A080461 A080462 * A080464 A080465 A080466

Keyword

base,easy,nonn,look

Author

Amarnath Murthy, Mar 02 2003

Extensions

More terms from Ray Chandler, Oct 11 2003

Extended to offset 0 and b-file by M. F. Hasler, Jan 10 2016

Status

approved