This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139245 #39 Dec 31 2023 10:21:29 %S A139245 4,24,44,64,84,104,124,144,164,184,204,224,244,264,284,304,324,344, %T A139245 364,384,404,424,444,464,484,504,524,544,564,584,604,624,644,664,684, %U A139245 704,724,744,764,784,804,824,844,864,884,904,924,944,964,984,1004,1024,1044 %N A139245 a(n) = 20*n - 16. %C A139245 Multiples of 4 with the unit digit equal to 4. %C A139245 Positive integers that are the product of two integers ending with 2 (see A017293). - _Stefano Spezia_, Jul 25 2021 %H A139245 Vincenzo Librandi, <a href="/A139245/b139245.txt">Table of n, a(n) for n = 1..2000</a> %H A139245 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1). %F A139245 a(n) = a(n-1) + 20. %F A139245 a(n) = 4*A016861(n-1). - _Wesley Ivan Hurt_, Jan 17 2014 %F A139245 From _Stefano Spezia_, Jul 25 2021: (Start) %F A139245 O.g.f.: 4*x*(1 + 4*x)/(1 - x)^2. %F A139245 E.g.f.: 16 + 4*exp(x)*(5*x - 4). %F A139245 a(n) = 2*a(n-1) - a(n-2) for n > 2. (End) %p A139245 A139245:=n->20*n-16; seq(A139245(n), n=1..100); # _Wesley Ivan Hurt_, Jan 17 2014 %t A139245 Range[4, 1500, 20] (* _Vladimir Joseph Stephan Orlovsky_, Jun 01 2011 *) %o A139245 (Magma) [20*n-16: n in [1..60]]; // _Vincenzo Librandi_, Jun 19 2011 %o A139245 (PARI) a(n)=20*n-16 \\ _Charles R Greathouse IV_, Aug 25 2014 %Y A139245 Subsequence of A034709, together with A017281, A017293, A139222, A017329, A139249, A139264, A139279 and A139280. %Y A139245 Cf. A017293. %K A139245 easy,nonn %O A139245 1,1 %A A139245 _Odimar Fabeny_, Jun 06 2008 %E A139245 More terms from _Reinhard Zumkeller_, Jun 22 2008