A129889 -id:A129889 - cp's OEIS frontend

A066106 a(2n) = (2n)(2n+2); a(2n+1) = 4n + 4.

0, 4, 8, 8, 24, 12, 48, 16, 80, 20, 120, 24, 168, 28, 224, 32, 288, 36, 360, 40, 440, 44, 528, 48, 624, 52, 728, 56, 840, 60, 960, 64, 1088, 68, 1224, 72, 1368, 76, 1520, 80, 1680, 84, 1848, 88, 2024, 92, 2208, 96, 2400, 100, 2600, 104, 2808, 108, 3024, 112

Offset: 0

George E. Antoniou, Dec 05 2001

Harry J. Smith, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,3,0,-3,0,1).

Flatten[Table[{(2n)(2n+2),4n+4},{n,0,30}]] (* Harvey P. Dale, May 14 2011 *)

{ for (n=0, 1000, if(n%2, a=2*n + 2, a=n*(n + 2)); write("b066106.txt", n, " ", a) ) } \\ Harry J. Smith, Nov 15 2009

G.f.: 4*x*(-1-2*x+x^2) / ( (x-1)^3*(1+x)^3 ). - Len Smiley, Dec 06 2001

a(n) = 4*A129889(n+1). - R. J. Mathar, Oct 31 2015

A120310 See comments lines.

Original entry on oeis.org

98, 72, 77, 49, 54, 20, 10, 1, 11, 2, 13, 4, 17, 8, 25, 7, 1, 2, 2, 6, 3, 12, 4, 20, 5, 15, 20, 13, 18, 11, 0, 0, 4, 9, 8, 18, 12, 27

Offset: 1

Sydney Richardson (AmyNStiers(AT)aol.com), Aug 16 2006

Comment from Joshua Zucker, May 26 2007. This appears to be a concatenation of five puzzles:
98,72,77,49,54,20,25,10,15,5,10,0,5,5,10,0,5,5,10,0,... (start with 98, then write down the product of its digits, then add 5, repeat) - see A129887.
10,1,11,2,13,4,17,8,25,7,... (start with 10; write down the sum of its digits; add last two terms; repeat) - see A129888.
1,2,2,6,3,12,4,20,5,30,6,42,... (write down n, then n(n+1)) - see A129889.
15,20,13,18,11,16,9,14,... (interleave two arithmetic progressions of difference -2).
0,0,4,9,8,18,12,27,16,36,20,... (interleave two arithmetic progressions 0,4,8,12,... and 0,9,18,27,...)

cp's OEIS Frontend

A066106 a(2n) = (2n)(2n+2); a(2n+1) = 4n + 4.

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A120310 See comments lines.

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