This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A167615 Total number of positive integers below 10^n with 4 positive squares in their representation as sum of squares. 4
 1, 15, 165, 1665, 16664, 166664, 1666663, 16666663, 166666661, 1666666662, 16666666661, 166666666660, 1666666666661, 16666666666660, 166666666666659, 1666666666666660, 16666666666666658, 166666666666666657, 1666666666666666660, 16666666666666666656 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A049416(n) + A180416(n) + A180425(n) + a(n) = A002283(n) LINKS Eric W. Weisstein: Lagrange's Four-Square Theorem. From MathWorld. Eric W. Weisstein: Sum of Squares Function. From MathWorld. FORMULA a(n) = Sum(ceil(10^n/2^(2*i+3)-7/8),i=0..k) with minimal k for which ceil(10^n/2^(2*k+3)-7/8) = 0 EXAMPLE a(1) = 1 since 7 is the only natural number below 10 which is the sum of 4 but no fewer nonzero squares MAPLE a:=proc(n)   local f, s, k;   f:=(x, y)->ceil(10^y/2^(2*x+3)-7/8):   s:=0:   for k from 0 by 1 while not f(k, n)=0 do     s:=s+f(k, n);   od:   return(s); end; CROSSREFS Cf. A004215 Sequence in context: A016291 A229406 A118093 * A210326 A016234 A160197 Adjacent sequences:  A167612 A167613 A167614 * A167616 A167617 A167618 KEYWORD nonn AUTHOR Martin Renner, Jan 18 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 19 00:03 EDT 2019. Contains 321305 sequences. (Running on oeis4.)