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A113972
Define b(0)=28, b(n+1)=2*b(n)+1; sequence gives largest prime factor of b(n).
1
7, 19, 23, 11, 463, 103, 53, 1237, 571, 101, 5939, 6599, 239, 313, 95027, 1223, 1900543, 281, 43441, 1699, 2339131, 2896067, 1283, 3229, 3021983, 5317369, 389231411, 32869, 301999, 2339, 2154169, 98383927, 25015877, 340939
OFFSET
0,1
COMMENTS
a(k) = 29*2^k-1 for k in A050540. - Robert Israel, Nov 23 2016
LINKS
FORMULA
a(n) = A006530(29*2^n-1). - Robert Israel, Nov 23 2016
EXAMPLE
a(2)=23 because b(1) = 2*28 + 1 = 57 and b(2) = 2*57 + 1 = 115 = 5*23.
MAPLE
with(numtheory): b:=proc(n): if n=0 then 28 else 2*b(n-1)+1 fi: end: a:=proc(n) local bb: bb:=factorset(b(n)): bb[nops(bb)] end: seq(a(n), n=0..38); # Emeric Deutsch, May 14 2006
CROSSREFS
Sequence in context: A125265 A023152 A123532 * A082422 A129812 A353046
KEYWORD
nonn
AUTHOR
Bill McEachen, Feb 06 2006
EXTENSIONS
More terms from Emeric Deutsch, May 14 2006
STATUS
approved