The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A097021 Initial terms of chains consisting of five consecutive integers, for neither of which the value of sigma-function is divisible by six. 1

%I

%S 211248,1146096,3948048,6090048,14590800,54100800,61051248,315758448,

%T 567777600,1715222448,1912711248,2408874048,2636106048,2744664048,

%U 2811450096,3304032048,4647444048,4832821296,6020336448,6028239600,6739372800,7824754800,10110704400

%N Initial terms of chains consisting of five consecutive integers, for neither of which the value of sigma-function is divisible by six.

%C In A084301, that is among remainders of sigma(n) modulo 6, chains of 0's can be large. On the contrary, the length of non-0-remainder-chains is believed to be limited or occurrence of longer chains is rare. Consider remainders of sigma(5x) modulo 6.

%C The first 1000 terms are all divisible by 144. - _Donovan Johnson_, Aug 07 2013

%H Donovan Johnson, <a href="/A097021/b097021.txt">Table of n, a(n) for n = 1..1000</a>

%e n = 14590800: sigma values for {n, n+1, n+2, n+3, n+4} = {59658880, 15110144, 22806063, 20958080, 25533914} have remainders modulo 6 as follows {4,2,3,2,2}.

%o (PARI) forstep(m=25, 10110704400, 25, if(sigma(m)%6<>0, n=m; c=1; forstep(j=m-1, m-4, -1, if(sigma(j)%6<>0, c++; n=j, j=m-4)); for(j=m+1, m+4, if(sigma(j)%6<>0, c++, j=m+4)); if(c>=5, print1(n ", ")))) /* _Donovan Johnson_, Aug 06 2013 */

%Y Cf. A084301.

%K nonn

%O 1,1

%A _Labos Elemer_, Aug 23 2004

%E a(6)-a(20) from _Donovan Johnson_, Sep 03 2008

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

Last modified December 3 00:23 EST 2022. Contains 358510 sequences. (Running on oeis4.)