A092383 Sum of digits of n if n odd, else sum of digits of 2n.

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

Offset

0,3

Comments

Inspired by Luhn algorithm for validating credit cards.

Links

Table of n, a(n) for n=0..86.

Formula

a(n) = sum of digits(if n odd then n else 2n).

Example

a(11) = 2 = 1 + 1 (1 and 1 are the digits in 11).
a(12) = 6 = 2 + 4 (2 and 4 are the digits in 24 = 2 * 12).

Mathematica

f[n_] := Plus @@ IntegerDigits[ If[ OddQ[n], n, 2n]]; Table[ f[n], {n, 0, 90}] (* Robert G. Wilson v, Mar 24 2004 *)

Crossrefs

Cf. A092384, A093150.

Sequence in context: A361316 A361782 A353990 * A227242 A156028 A021232

Adjacent sequences: A092380 A092381 A092382 * A092384 A092385 A092386

Keyword

easy,nonn,base

Author

Semaphore Corporation (help(AT)semaphorecorp.com), Mar 20 2004

Extensions

Corrected and extended by Ray Chandler, Mar 21 2004

Status

approved