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A072259 ((6n+37)*4^n-1)/3. 4
12, 57, 261, 1173, 5205, 22869, 99669, 431445, 1856853, 7951701, 33903957, 144004437, 609572181, 2572506453, 10826896725, 45455070549, 190410216789, 796000605525, 3321441375573 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Related to Collatz function (for n>0). All divisible by 3.

LINKS

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (9,-24,16).

FORMULA

G.f.: 3*(4-17*x+12*x^2)/((1-x)*(1-4*x)^2). - Bruno Berselli, Dec 16 2011

PROG

(PARI) a(n)=((6*n+37)*4^n-1)/3 \\ Charles R Greathouse IV, Oct 07 2015

CROSSREFS

Cf. A072257, A072258, A072260.

Sequence in context: A212065 A121693 A190297 * A272233 A242983 A167533

Adjacent sequences:  A072256 A072257 A072258 * A072260 A072261 A072262

KEYWORD

nonn,easy

AUTHOR

N. Rathankar (rathankar(AT)yahoo.com), Jul 08 2002

EXTENSIONS

Edited and extended by Henry Bottomley, Aug 06 2002

STATUS

approved

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Last modified December 8 18:55 EST 2016. Contains 278948 sequences.