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A164005 Zero together with row 5 of the array in A163280. 3
0, 7, 14, 21, 32, 45, 60, 77, 96, 117, 140, 165, 192, 221, 252, 285, 320, 357, 396, 437, 480, 525, 572, 621, 672, 725, 780, 837, 896, 957, 1020, 1085, 1152, 1221, 1292, 1365, 1440, 1517, 1596, 1677, 1760, 1845, 1932, 2021, 2112, 2205, 2300, 2397, 2496, 2597 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

This sequence should be compared with A100451! (See A163280.)

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..5000

Index entries for linear recurrences with constant coefficients, signature (3, -3, 1).

FORMULA

From G. C. Greubel, Aug 28 2017: (Start)

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

a(n) = n*(n+4), n >= 3.

G.f.: x*(7 - 7*x + 4*x^3 - 2*x^4)/(1 - x)^3.

E.g.f.: x*(x+5)*exp(x) + 2*x + x^2. (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: A164005 := proc(n) if n = 0 then 0; else A163280(5, n) ; fi; end: seq(A164005(n), n=0..80) ; # R. J. Mathar, Aug 09 2009

MATHEMATICA

Join[{0, 7, 14}, Table[n*(n + 4), {n, 3, 50}]] (* G. C. Greubel, Aug 28 2017 *)

PROG

(PARI) x='x+O('x^50); concat([0], Vec(x*(7 - 7*x + 4*x^3 - 2*x^4)/(1 - x)^3)) \\ G. C. Greubel, Aug 28 2017

CROSSREFS

Cf. A008578, A161344, A161345, A163280, A164000, A164004, A164006.

Cf. A028347. [R. J. Mathar, Aug 09 2009]

Sequence in context: A044832 A033004 A189931 * A100451 A028555 A061823

Adjacent sequences:  A164002 A164003 A164004 * A164006 A164007 A164008

KEYWORD

nonn

AUTHOR

Omar E. Pol, Aug 08 2009

EXTENSIONS

Extended by R. J. Mathar, Aug 09 2009

STATUS

approved

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Last modified June 20 10:13 EDT 2019. Contains 324234 sequences. (Running on oeis4.)