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A073033 A 4-cycle of the k => sigma(k)-k process, where sigma(k) is the sum of divisors of k (A000203). 1
18656380, 20522060, 28630036, 24289964, 18656380, 20522060, 28630036, 24289964, 18656380, 20522060, 28630036, 24289964, 18656380, 20522060, 28630036, 24289964, 18656380, 20522060, 28630036, 24289964, 18656380, 20522060, 28630036, 24289964 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
18656380 = 2^2*5*932819, 20522060 = 2^2*5*13*17*4643, 28630036 = 2^2*19*449*839, 24289964 = 2^2*97*62603.
The cycle was discovered by Cohen (1970). - Amiram Eldar, Aug 18 2024
LINKS
Henri Cohen, On amicable and sociable numbers, Math. Comp., Vol. 24, No. 110 (1970), pp. 423-429.
PROG
(PARI) a(n)=[24289964, 18656380, 20522060, 28630036][n%4+1] \\ Charles R Greathouse IV, Feb 19 2013
CROSSREFS
Sequence in context: A209959 A140171 A185854 * A251389 A138025 A184790
KEYWORD
nonn,easy,changed
AUTHOR
Miklos Kristof, Aug 22 2002
STATUS
approved

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Last modified August 31 22:14 EDT 2024. Contains 375574 sequences. (Running on oeis4.)