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A017605
a(n) = 12*n + 7.
12
7, 19, 31, 43, 55, 67, 79, 91, 103, 115, 127, 139, 151, 163, 175, 187, 199, 211, 223, 235, 247, 259, 271, 283, 295, 307, 319, 331, 343, 355, 367, 379, 391, 403, 415, 427, 439, 451, 463, 475, 487, 499, 511, 523, 535, 547, 559, 571, 583, 595, 607, 619, 631
OFFSET
0,1
FORMULA
a(n) = 2*(12*n+1) - a(n-1) = 2*a(n-1) - a(n-2) with a(0) = 7, a(1) = 19. - Vincenzo Librandi, Nov 19 2010
a(n) = (n+1)*A016921(n+1) - n*A016921(n). - Bruno Berselli, Jan 18 2013
a(n) = A003215(n+1) - 6*A000217(n-1). - Leo Tavares, Jul 25 2021
From Elmo R. Oliveira, Apr 02 2024: (Start)
G.f.: (7+5*x)/(1-x)^2.
E.g.f.: exp(x)*(7 + 12*x).
a(n) = A049453(n+1) - A049453(n) = A142241(n)/2. (End)
MATHEMATICA
12*Range[0, 200] + 7 (* Vladimir Joseph Stephan Orlovsky, Feb 19 2011 *)
PROG
(Sage) [i+7 for i in range(525) if gcd(i, 12) == 12] # Zerinvary Lajos, May 21 2009
(PARI) a(n)=12*n+7 \\ Charles R Greathouse IV, Jul 10 2016
KEYWORD
nonn,easy
STATUS
approved