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A173012
a(1) = 1, for n >= 2; a(n) = the smallest number h such that sigma(h) = A000203(h) = a(n-1) + 2, a(n) = 0 if no such number exists.
4
1, 2, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
OFFSET
1,2
COMMENTS
a(1) = 1, a(2) = 2, a(3) = 3, a(n) = 0 for n >= 4.
FORMULA
A000203(a(n)) = a(n-1) + 2 for n >= 2.
PROG
(PARI) a(n)=if(n>3, 0, n) \\ Charles R Greathouse IV, Feb 14 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jaroslav Krizek, Nov 06 2010
STATUS
approved