# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a227249 Showing 1-1 of 1 %I A227249 #31 Dec 02 2018 02:45:12 %S A227249 1,4,6,21,80,4151,6982,269563,779693,834365,16176645,19770092, %T A227249 41049539,228612936,1950787140,2404785364,3095996836,5236785750 %N A227249 Number of consecutive composites beginning with the first, to be added to obtain a power. %C A227249 All powers are squares with the exception of 3^3 for a(2) and 6^9 for a(6). I conjecture these are the only nonsquare powers. %C A227249 a(19) > 10^10. - _Zak Seidov_, Jul 06 2013 %F A227249 {n: A053767(n) in A001597}. - _Zak Seidov_, Jul 06 2013 %e A227249 Considering 1 not to be prime and not to be composite, first composite is 4 which is 2^2. And the sum of the first four composites is 4 + 6 + 8 + 9 = 27 = 3^3. %p A227249 # see A001597 for isA001597 %p A227249 for n from 1 do %p A227249 if isA001597(A053767(n) ) then %p A227249 print(n) ; %p A227249 end if; %p A227249 end do: # _R. J. Mathar_, Jul 08 2013 %o A227249 (PARI) : n=10^7;v=vector(n);i=0;for(a=2,n,if(isprime(a),next,i++;v[i]=a));k=0;for(j=1,i,k=k+v[j];if(ispower(k,,&n),print1([k,n,j]," "))) %Y A227249 Cf. A001597, A002808, A053767, A141092. %K A227249 nonn,more %O A227249 1,2 %A A227249 _Robin Garcia_, Jul 04 2013 %E A227249 a(11) - a(18) from _Zak Seidov_, Jul 06 2013 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE