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Search: id:A072261
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| A072261 |
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a(n)=4*a(n-1)+1, a(1)=7. |
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+0
4
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| 7, 29, 117, 469, 1877, 7509, 30037, 120149, 480597, 1922389, 7689557, 30758229, 123032917, 492131669, 1968526677, 7874106709, 31496426837, 125985707349, 503942829397, 2015771317589, 8063085270357, 32252341081429
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OFFSET
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1,1
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COMMENT
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These are the integers N which on application of the Collatz function yield the number 11. The Collatz function: if N is an odd number then (3N+1)/2^r yields a positive odd integer for some value of r (which in this case is 11).
These numbers reach 11 in Collatz function iteration after 2(n+1) steps and so end in 1 after exactly 2n+18 steps. - Lambert Klasen (lambert.klasen(AT)gmx.de), Nov 08 2004
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FORMULA
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22*((4^n - 1)/3)+7 = 22*A002450(n)+7 - Lambert Klasen (lambert.klasen(AT)gmx.de), Nov 08 2004
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MATHEMATICA
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a[n_] := 4a[n - 1] + 1; a[1] = 7; Table[ a[n], {n, 1, 25}]
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CROSSREFS
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Cf. A072257, A072258, A072259, A072260 & A072262.
Adjacent sequences: A072258 A072259 A072260 this_sequence A072262 A072263 A072264
Sequence in context: A124828 A037094 A118171 this_sequence A066744 A037576 A055427
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KEYWORD
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nonn
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AUTHOR
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N. Rathankar (rathankar(AT)yahoo.com), Jul 08 2002
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 17 2002
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