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A118912
a(1) = 2; a(n) is greatest prime < a(n-1)^4.
1
2, 13, 28559, 665230244078823349, 195833931687186822327230545227550596864953022841534058316595001440791433
OFFSET
1,1
COMMENTS
Exponent-4 analog of A059785 a(n+1)=prevprime(a(n)^2), with exponent 3 being A118910 a(1) = 2; a(n) is greatest prime < a(n-1)^3.
FORMULA
a(1) = 2; a(n) is greatest prime < a(n-1)^4.
EXAMPLE
a(1) = 2, by definition.
a(2) = 13 = 2^4 - 3.
a(3) = 28559 = 13^4 - 2.
a(4) = 665230244078823349 = 28559^4 - 12.
a(5) = 195833931687186822327230545227550596864953022841534058316595001440791433 = 665230244078823349^4 - 168.
a(6) is too large to include.
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, May 05 2006
STATUS
approved