The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A074149 Sum of terms in each group in A074147. 6
 1, 6, 15, 36, 65, 114, 175, 264, 369, 510, 671, 876, 1105, 1386, 1695, 2064, 2465, 2934, 3439, 4020, 4641, 5346, 6095, 6936, 7825, 8814, 9855, 11004, 12209, 13530, 14911, 16416, 17985, 19686, 21455, 23364, 25345, 27474, 29679, 32040, 34481, 37086 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The odd-indexed entries are the sums pertaining to the corresponding magic squares. LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (2,1,-4,1,2,-1). FORMULA a(2n-1) = 4n^3 - 6n^2 + 4n - 1, a(2n) = 4n^3 + 2n. a(n) = (n^3 + n)/2 if n odd, n^3/2 + n if n even. a(n) = n^3/2 + n(3 + (-1)^n)/4. - Franklin T. Adams-Watters, Jul 17 2006 G.f.: x*(x^2+1)*(x^2+4*x+1) / ( (1+x)^2*(x-1)^4 ). - R. J. Mathar, Mar 07 2011 E.g.f.: x*((2 + 3*x + x^2)*cosh(x) + (3 + 3*x + x^2)*sinh(x))/2. - Stefano Spezia, May 07 2021 a(n) = n*(n^2-A000035(n))/2 + n. - Chai Wah Wu, Aug 30 2022 MATHEMATICA LinearRecurrence[{2, 1, -4, 1, 2, -1}, {1, 6, 15, 36, 65, 114}, 50] (* Harvey P. Dale, Jun 22 2016 *) PROG (PARI) a(n)=n^3/2 + n*(3+(-1)^n)/4 \\ Charles R Greathouse IV, Jun 11 2015 (Python) def A074149(n): return (n*(n**2-(n&1))>>1)+n # Chai Wah Wu, Aug 30 2022 CROSSREFS Cf. A000035, A074147, A074148, A061925, A006003, A061804. Sequence in context: A273861 A074132 A269543 * A273411 A273490 A324221 Adjacent sequences: A074146 A074147 A074148 * A074150 A074151 A074152 KEYWORD nonn,easy AUTHOR Amarnath Murthy, Aug 28 2002 EXTENSIONS More terms from Franklin T. Adams-Watters, Jul 17 2006 STATUS approved

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

Last modified March 28 07:43 EDT 2023. Contains 361577 sequences. (Running on oeis4.)