

A092384


Sum of digits of n if n even, else sum of digits of 2n.


2



0, 2, 2, 6, 4, 1, 6, 5, 8, 9, 1, 4, 3, 8, 5, 3, 7, 7, 9, 11, 2, 6, 4, 10, 6, 5, 8, 9, 10, 13, 3, 8, 5, 12, 7, 7, 9, 11, 11, 15, 4, 10, 6, 14, 8, 9, 10, 13, 12, 17, 5, 3, 7, 7, 9, 2, 11, 6, 13, 10, 6, 5, 8, 9, 10, 4, 12, 8, 14, 12, 7, 7, 9, 11, 11, 6, 13, 10, 15, 14, 8, 9, 10, 13, 12, 8, 14, 12, 16
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OFFSET

0,2


COMMENTS

Inspired by Luhn algorithm for validating credit cards.


LINKS

Table of n, a(n) for n=0..88.


FORMULA

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


EXAMPLE

a(11) = 4 = 2 + 2 (2 and 2 are the digits in 22 = 2 * 11).
a(12) = 3 = 1 + 2 (1 and 2 are the digits in 12).


MATHEMATICA

f[n_] := Plus @@ IntegerDigits[ If[ EvenQ[n], n, 2n]]; Table[ f[n], {n, 0, 90}] (* Robert G. Wilson v, Mar 24 2004 *)
Table[If[EvenQ[n], Total[IntegerDigits[n]], Total[IntegerDigits[2n]]], {n, 0, 120}] (* Harvey P. Dale, Mar 18 2019 *)


CROSSREFS

Cf. A092383, A093150.
Sequence in context: A334870 A324122 A324349 * A061915 A138565 A137316
Adjacent sequences: A092381 A092382 A092383 * A092385 A092386 A092387


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



