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A173013
a(1) = 1, for n >= 2; a(n) = the smallest number h such that sigma(h) = A000203(h) = a(n-1) + 3, a(n) = 0 if no such number exists.
4
1, 3, 5, 7, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2
OFFSET
1,2
COMMENTS
a(n) is eventually periodic sequence with period (0, 2).
FORMULA
A000203(a(n)) = a(n-1) + 3 for n >= 2.
PROG
(PARI) a(n)=if(n>4, 2-n%2*2, 2*n-1) \\ Charles R Greathouse IV, Feb 14 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jaroslav Krizek, Nov 06 2010
STATUS
approved