The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A225720 Composite squarefree numbers n such that p+10 divides n-10 for each prime p dividing n. 33
 10, 79222, 206965, 784090, 1673122, 2227123, 4798090, 5202571, 9196330, 13146715, 15015430, 18213595, 19342333, 21735010, 27907435, 28234018, 28240090, 37394146, 38710990, 53990695, 54772453, 70646509, 79671826, 89678830, 107251990, 114572545, 115005187, 137245690 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE Prime factors of 2227123 are 19, 251 and 467. We have that (2227123-10)/(19+10) = 76797, (2227123-10)/(251+10) = 8533 and (2227123-10)/(467+10) = 4669. MAPLE with(numtheory); A225720:=proc(i, j) local c, d, n, ok, p, t; for n from 2 to i do if not isprime(n) then p:=ifactors(n)[2]; ok:=1; for d from 1 to nops(p) do if p[d][2]>1 or p[d][1]=j then ok:=0; break; fi; if  not type((n+j)/(p[d][1]-j), integer) then ok:=0; break; fi; od; if ok=1 then print(n); fi; fi; od; end: A225720(10^9, -10); PROG (PARI) is(n, f=factor(n))=if(#f[, 2]<2 || vecmax(f[, 2])>1, return(0)); for(i=1, #f~, if((n-10)%(f[i, 1]+10), return(0))); 1 \\ Charles R Greathouse IV, Nov 05 2017 CROSSREFS Cf. A208728, A225702-A225719. Sequence in context: A048832 A225070 A115673 * A013792 A139106 A307927 Adjacent sequences:  A225717 A225718 A225719 * A225721 A225722 A225723 KEYWORD nonn AUTHOR Paolo P. Lava, May 13 2013 EXTENSIONS a(20)-a(27) from Donovan Johnson, Nov 15 2013 a(28) from Charles R Greathouse IV, Nov 05 2017 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 June 24 17:51 EDT 2021. Contains 345419 sequences. (Running on oeis4.)