0,1

This sequence is not periodic because log(4)/log(10) is an irrational number. - T. D. Noe (noe(AT)sspectra.com), Jan 25 2007

a(n)=Number_of_digits{4^(n+1)}-Number_of digits{4^(n)} with n>=0 and where "Number_of digits" is a hypothetical function giving the number of digits of the argument

a(1)=1 because 4^(1+1)=16 (two digits) 4^1=4 (one digit) and the difference is 1 a(2)=0 because 4^(2+1)=64 (two digits) 4^(2)=16 (two digits) and the difference is 0

P:=proc(n) local i, j, k, w, old; k:=4; for i from 1 by 1 to n do j:=k^i; w:=0; while j>0 do w:=w+1; j:=trunc(j/10); od; if i>1 then print(w-old); old:=w; else old:=w; fi; od; end: P(1000);

Cf. A125117, A125122.

Sequence in context: A024711 A128174 A096055 this_sequence A115198 A005614 A071036

Adjacent sequences: A125141 A125142 A125143 this_sequence A125145 A125146 A125147

easy,nonn

Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Jan 11 2007