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A055263
a(n) = Sum of digits of (n + a(n-1)).
8
0, 1, 3, 6, 1, 6, 3, 1, 9, 9, 10, 3, 6, 10, 6, 3, 10, 9, 9, 10, 3, 6, 10, 6, 3, 10, 9, 9, 10, 12, 6, 10, 6, 12, 10, 9, 9, 10, 12, 6, 10, 6, 12, 10, 9, 9, 10, 12, 6, 10, 6, 12, 10, 9, 9, 10, 12, 15, 10, 15, 12, 10, 9, 9, 10, 12, 15, 10, 15, 12, 10, 9, 9, 10, 12, 15, 10, 15, 12, 10, 9, 9, 10
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
FORMULA
a(n) = A007953(A055262(n)) = A007953(n + a(n-1)).
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
Sequence in context: A355072 A134804 A145389 * A004157 A331514 A091068
KEYWORD
base,easy,nonn
AUTHOR
Henry Bottomley, May 08 2000
EXTENSIONS
More terms from Paolo P. Lava, Jul 31 2007
STATUS
approved