OFFSET
0,3
COMMENTS
If n=0 or 8 mod 9, then a(n)=0 mod 9; if n=1, 4 or 7 mod 9, then a(n)=1 mod 9; if n=2 or 6 mod 9, then a(n)=3 mod 9; if n=3 or 5 mod 9, then a(n)=6 mod 9.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
EXAMPLE
a(13)=10 because a(12)=6, 13 + 6 = 19 and 1 + 9 = 10.
MATHEMATICA
nxt[{n_, a_}]:={n+1, Total[IntegerDigits[n+a+1]]}; Transpose[NestList[nxt, {0, 0}, 90]][[2]] (* Harvey P. Dale, Aug 11 2016 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Henry Bottomley, May 08 2000
EXTENSIONS
More terms from Paolo P. Lava, Jul 31 2007
STATUS
approved