login
This site is supported by donations to The OEIS Foundation.

 

Logo

The OEIS is looking to hire part-time people to help edit core sequences, upload scanned documents, process citations, fix broken links, etc. - Neil Sloane, njasloane@gmail.com

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A164004 Zero together with row 4 of the array in A163280. 6
0, 5, 10, 18, 28, 40, 54, 70, 88, 108, 130, 154, 180, 208, 238, 270, 304, 340, 378, 418, 460, 504, 550, 598, 648, 700, 754, 810, 868, 928, 990, 1054, 1120, 1188, 1258, 1330, 1404, 1480, 1558, 1638, 1720, 1804, 1890, 1978, 2068, 2160, 2254, 2350, 2448, 2548 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..49.

FORMULA

Conjectures from Colin Barker, Apr 07 2015: (Start)

a(n) = n*(3+n) for n > 1.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 4.

G.f.: x*(x^3 - 3*x^2 + 5*x - 5) / (x-1)^3.

(End)

MAPLE

A033676 := proc(n) local a, d; a := 0 ; for d in numtheory[divisors](n) do if d^2 <= n then a := max(a, d) ; fi; od: a; end: A163280 := proc(n, k) local r, T ; r := 0 ; for T from k^2 by k do if A033676(T) = k then r := r+1 ; if r = n then RETURN(T) ; fi; fi; od: end: A164004 := proc(n) if n = 0 then 0; else A163280(4, n) ; fi; end: seq(A164004(n), n=0..80) ; # R. J. Mathar, Aug 09 2009

CROSSREFS

Cf. A008578, A161344, A161345, A163280, A164000, A005563, A164005.

Cf. A028552.

Sequence in context: A092390 A035608 A091386 * A025010 A058555 A226445

Adjacent sequences:  A164001 A164002 A164003 * A164005 A164006 A164007

KEYWORD

nonn

AUTHOR

Omar E. Pol, Aug 08 2009

EXTENSIONS

Extended beyond a(12) by R. J. Mathar, Aug 09 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 26 01:26 EDT 2017. Contains 287073 sequences.