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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A027692 a(n) = n^2 + n + 7. 7
7, 9, 13, 19, 27, 37, 49, 63, 79, 97, 117, 139, 163, 189, 217, 247, 279, 313, 349, 387, 427, 469, 513, 559, 607, 657, 709, 763, 819, 877, 937, 999, 1063, 1129, 1197, 1267, 1339, 1413, 1489, 1567, 1647, 1729, 1813, 1899, 1987, 2077, 2169, 2263 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Integers k for which the discriminant of x^3-kx-k is a square. - Jacob A. Siehler, Mar 14 2009

For n > 2: a(n) = A176271(n+1,4). - Reinhard Zumkeller, Apr 13 2010

LINKS

Muniru A Asiru, Table of n, a(n) for n = 0..3000

P. De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X)

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

FORMULA

a(n) = 2*n + a(n-1) (with a(0)=7). - Vincenzo Librandi, Aug 05 2010

G.f.: (-7 + 12*x - 7*x^2) / (x-1)^3. - R. J. Mathar, Feb 06 2011

a(n+1) = n^2+3*n+9, see A005471. - R. J. Mathar, Jun 06 2019

a(n) mod 6 = A109007(n+2). - R. J. Mathar, Jun 06 2019

MAPLE

A027692 := proc(n)

    n*(n+1)+7 ;

end proc: # R. J. Mathar, Jun 06 2019

MATHEMATICA

f[n_]:=n^2+n+7; f[Range[0, 60]] (* Vladimir Joseph Stephan Orlovsky, Feb 06 2011 *)

PROG

(PARI) a(n)=n^2+n+7 \\ Charles R Greathouse IV, Jun 11 2015

(GAP) List([0..50], n->n^2+n+7); # Muniru A Asiru, Jul 15 2018

CROSSREFS

Cf. A002522, A005471 (subset of primes).

Sequence in context: A129069 A258616 A125866 * A297063 A185720 A032487

Adjacent sequences:  A027689 A027690 A027691 * A027693 A027694 A027695

KEYWORD

nonn,easy

AUTHOR

Patrick De Geest

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 14 14:50 EST 2019. Contains 329979 sequences. (Running on oeis4.)