OFFSET
1,1
COMMENTS
Appearances to the contrary, this sequence is not recursive with a geometric progression factor of 1024. Examples of a(n+1)/a(n) which are not 1024 are a(10)/a(9) = a(20)/a(19) = a(30)/a(29) = a(57)/a(56) = a(67)/a(66) = 2^106 or a(39)/a(38) = a(48)/a(47)= a(86)/a(85) = 2^116. - R. J. Mathar, Jan 10 2008
Therefore this sequence differs from A013830. - Georg Fischer, Oct 06 2018
LINKS
Muniru A Asiru, Table of n, a(n) for n = 1..71
Tanya Khovanova, Non Recursions
FORMULA
a(n) = 4^A242594(n).
MATHEMATICA
DeleteCases[Table[If[StringStartsQ[ToString[4^n], "4"], 4^n], {n, 100}], Null] (* Stefano Spezia, Oct 06 2018 *)
PROG
(GAP) Filtered(List([0..100], n->4^n), i->ListOfDigits(i)[1]=4); # Muniru A Asiru, Oct 06 2018
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Feb 09 2002
STATUS
approved