A121022 - OEIS

%I #28 Nov 02 2022 13:47:58

%S 2,12,20,22,24,26,28,32,42,52,62,72,82,92,102,112,120,122,124,126,128,

%T 132,142,152,162,172,182,192,200,202,204,206,208,210,212,214,216,218,

%U 220,222,224,226,228,230,232,234,236,238,240,242,244,246,248,250,252

%N Even numbers containing a 2 in their decimal representation.

%H Reinhard Zumkeller, <a href="/A121022/b121022.txt">Table of n, a(n) for n = 1..10000</a>

%H Seong Ju Kim, R. Stees, L. Taalman, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL19/Stees/stees4.html">Sequences of Spiral Knot Determinants</a>, Journal of Integer Sequences, Vol. 19 (2016), # 16.1.4.

%H Ryan Stees, <a href="https://commons.lib.jmu.edu/honors201019/84">Sequences of Spiral Knot Determinants</a>, Senior Honors Projects, Paper 84, James Madison Univ., May 2016.

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.

%F a(n) ~ 2n. - _Charles R Greathouse IV_, Mar 30 2022

%t Select[2*Range[200],DigitCount[#,10,2]>0&] (* _Harvey P. Dale_, Nov 04 2013 *)

%o (Haskell)

%o a121022 n = a121022_list !! (n-1)

%o a121022_list = filter (('2' `elem`) . show) [0, 2 ..]

%o -- _Reinhard Zumkeller_, Nov 08 2013

%o (PARI) is(n) = n%2==0 && setsearch(vecsort(digits(n)), 2) \\ _Felix Fröhlich_, Nov 22 2020

%Y Intersection of A005843 and A011532.

%Y Cf. A121041, A011531, A121023, A121024, A121025, A121026, A121027, A121028, A121029, A121030, A121031, A121032, A121033, A121034, A121035, A121036, A121037, A121038, A121039, A121040.

%K nonn,base,easy

%O 1,1

%A _Reinhard Zumkeller_, Jul 21 2006