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A225720
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Composite squarefree numbers n such that p+10 divides n-10 for each prime p dividing n.
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33
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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
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OFFSET
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1,1
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LINKS
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EXAMPLE
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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.
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MAPLE
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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);
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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