A293880 - OEIS

%I #15 Feb 18 2024 08:29:37

%S 20,120,200,201,202,203,204,205,206,207,208,209,220,320,420,520,620,

%T 720,820,920,1020,1120,1200,1201,1202,1203,1204,1205,1206,1207,1208,

%U 1209,1220,1320,1420,1520,1620,1720,1820,1920,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010

%N Numbers having '20' as substring of their digits.

%C Row 20 of A292690 and A293869. A121040 lists the terms which are divisible by 19.

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

%F a(n) ~ n. - _Charles R Greathouse IV_, Nov 02 2022

%t Select[Range[2100],SequenceCount[IntegerDigits[#],{2,0}]>0&] (* _Harvey P. Dale_, Jul 25 2021 *)

%o (PARI) is_A293880 = has(n, p=20, m=10^#Str(p))=until(p>n\=10, n%m==p&&return(1))

%Y Cf. A292690, A293869.

%Y Cf. A011540, A011531, A011532, A011533, A011534, A011535, A011536, A011537, A011538, A011539: analog for '0' - '9'.

%Y Cf. A293870, A293871, A293872, A293873, A293874, A293875, A293876, A293877, A293878, A293879: same for '10' - '19'.

%Y Cf. A121041, A121022, A121023, A121024, A121025, A121026, A121027, A121028, A121029, A121030, A121031, A121032, A121033, A121034, A121035, A121036, A121037, A121038, A121039, A121040: subsequences of the above, containing only multiples of the pattern p.

%K nonn,base,easy

%O 1,1

%A _M. F. Hasler_, Oct 18 2017