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A139613
a(n) = 78*n + 13.
4
13, 91, 169, 247, 325, 403, 481, 559, 637, 715, 793, 871, 949, 1027, 1105, 1183, 1261, 1339, 1417, 1495, 1573, 1651, 1729, 1807, 1885, 1963, 2041, 2119, 2197, 2275, 2353, 2431, 2509, 2587, 2665, 2743, 2821, 2899, 2977, 3055, 3133
OFFSET
0,1
COMMENTS
Numbers of the 13th column of positive numbers in the square array of nonnegative and polygonal numbers A139600. Also, numbers of the 13th column in the square array A057145.
FORMULA
From Elmo R. Oliveira, Apr 03 2024: (Start)
G.f.: 13*(1+5*x)/(x-1)^2.
E.g.f.: 13*exp(x)*(1 + 6*x).
a(n) = 13*A016921(n).
a(n) = 2*a(n-1) - a(n-2) for n >= 2. (End)
MATHEMATICA
78*Range[0, 50] + 13 (* Paolo Xausa, Apr 04 2024 *)
PROG
(Magma) [13*(6*n + 1): n in [0..60]]; // Vincenzo Librandi, Jul 23 2011
(PARI) a(n)=78*n+13 \\ Charles R Greathouse IV, Oct 05 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Apr 27 2008
STATUS
approved