A225716 Composite squarefree numbers n such that p(i)+6 divides n-6, where p(i) are the prime factors of n.

6, 26781, 120791, 5099531, 5720435, 14637451, 24110358, 31552261, 33792198, 57804181, 71925054, 88324781, 92849126, 441031331, 650715071, 924029951, 1425902869, 2093676486, 2336689491, 3273172441, 4533042611, 4711366831, 5162021871, 5502040431, 6427899582

Offset

1,1

Links

Table of n, a(n) for n=1..25.

Example

Prime factors of 14637451 are 41, 229 and 1559. We have that (14637451-6)/(41+6) = 311435, (14637451-6)/(229+6) = 62287 and (14637451-6)/(1559+6) = 9353.

Maple

with(numtheory); A225716:=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: A225716(10^9, -6);

Crossrefs

Cf. A208728, A225702-A225715, A225717-A225720.

Sequence in context: A368064 A337990 A143780 * A159429 A367944 A283888

Adjacent sequences: A225713 A225714 A225715 * A225717 A225718 A225719

Keyword

nonn

Author

Paolo P. Lava, May 13 2013

Extensions

a(14)-a(25) from Donovan Johnson, Nov 15 2013

Status

approved