A225714 Composite squarefree numbers n such that p(i)+4 divides n-4, where p(i) are the prime factors of n.

1054, 9541, 91039, 371074, 985054, 1043959, 1063003, 1107754, 1162498, 1357339, 1786054, 4018018, 5368549, 5820154, 8725747, 9994954, 12402709, 17138503, 17914054, 20855839, 23116009, 25077199, 26545054, 29247229, 30308359, 31424419, 33892759, 44141629

Offset

1,1

Links

Table of n, a(n) for n=1..28.

Example

Prime factors of 1043959 are 7, 293 and 509. We have that (1043959-4)/(7+4) = 94905, (1043959-4)/(293+4) = 3515 and (1043959-4)/(509+4) = 2035.

Maple

with(numtheory); A225714:=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: A225714(10^9, -4);

Crossrefs

Cf. A208728, A225702-A225713, A225715-A225720.

Sequence in context: A090005 A339249 A359624 * A158692 A236905 A281079

Adjacent sequences: A225711 A225712 A225713 * A225715 A225716 A225717

Keyword

nonn

Author

Paolo P. Lava, May 13 2013

Extensions

a(20)-a(28) from Donovan Johnson, Nov 15 2013

Status

approved