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A086360
Fixed point if (decimal-digit-sum)-function at initial value = n-th primorial = A002110(n) is iterated.
3
2, 6, 3, 3, 6, 6, 3, 3, 6, 3, 3, 3, 6, 6, 3, 6, 3, 3, 3, 6, 6, 6, 3, 6, 6, 3, 3, 6, 6, 3, 3, 6, 3, 3, 6, 6, 6, 6, 3, 6, 3, 3, 6, 6, 3, 3, 3, 3, 6, 6, 3, 6, 6, 3, 6, 3, 6, 6, 6, 3, 3, 6, 6, 3, 3, 6, 6, 6, 3, 3, 6, 3, 3, 3, 3, 6, 3, 3, 6, 6, 3, 3, 6, 6, 6, 3, 6
OFFSET
1,1
LINKS
FORMULA
a(n) = A010888(A002110(n)) = fixed-point of A007953(A002110(n));
a(n) = n-th primorial modulo(9).
Only a(1)=2; each subsequent term is a 3 or a 6.
EXAMPLE
For n=7, 7th primorial = 510510, iteration list = {510510,12,3}, so a(7)=3.
MAPLE
A086360 := proc(n) option remember: if(n=1)then return 2:fi: return ithprime(n)*procname(n-1) mod 9: end: seq(A086360(n), n=1..100); # Nathaniel Johnston, May 04 2011
MATHEMATICA
sud[x_] := Apply[Plus, DeleteCases[IntegerDigits[x], 0]] q[x_] := Apply[Times, Table[Prime[w], {w, 1, x}]] Table[FixedPoint[sud, q[w]], {w, 1, 128}]
KEYWORD
base,easy,nonn
AUTHOR
Labos Elemer, Jul 21 2003
STATUS
approved