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A214266
Numbers n such that n, phi(n) and sigma(n) have same set of prime factors.
1
1, 103654150315463023813006470, 207308300630926047626012940, 414616601261852095252025880, 518270751577315119065032350, 829233202523704190504051760, 982794906694760522078876160, 1036541503154630238130064700
OFFSET
1,2
LINKS
Prime Puzzles, Puzzle 451
EXAMPLE
For n = 207308300630926047626012940 = 2^2*3^4*5*7*11*13^3*17^3*29^2*31^3*37^2*67^2
phi(n) = 2^18*3^9*5^2*7*11*13^2*17^2*29*31^2*37*67 and
sigma(n) = 2^16*3^6*5^2*7^5*11^2*13^2*17*29*31*37*67^2
have the same prime factors.
CROSSREFS
KEYWORD
nonn,fini
AUTHOR
Michel Marcus, Jul 09 2012
STATUS
approved