A164005 Zero together with row 5 of the array in A163280.

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

Offset

0,2

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

Conjecture: a(n) = A100451(n+2). (See A163280.)

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.

Sequence in context: A044832 A033004 A189931 * A100451 A028555 A061823

Adjacent sequences: A164002 A164003 A164004 * A164006 A164007 A164008

Keyword

nonn,easy

Author

Omar E. Pol, Aug 08 2009

Extensions

Extended by R. J. Mathar, Aug 09 2009

Status

approved