A283527 First of three consecutive Sophie Germain semiprimes: n, n+1 and n+2 are all terms of A111153.

15117, 17245, 34413, 93453, 143101, 157713, 190621, 208293, 233097, 294301, 323281, 346497, 470341, 501477, 1306113, 1337221, 1346401, 1655853, 1682313, 1774801, 1877613, 1879021, 1933233, 1976041

Offset

1,1

Comments

All terms are 1 mod 4, see A056809.

Links

Zak Seidov, Table of n, a(n) for n = 1..408

Mathematica

  po[x_] := PrimeOmega[x];   Select[Range[15117, 200000, 2],
2 == po[#] == po[2*# + 1] ==po[# + 1] == po[2*# + 3] == po[# + 2] ==
po[2*# + 5] &]

Prog

(PARI) {bo(x)=bigomega(x)
forstep(n=15117, 2000000, 2, if(
2 == bo(n) && 2 == bo(n+1) && 2 == bo(n+2) && 2 == bo(2*n+1) &&
2 == bo(2*n+3) && 2 == bo(2*n+5), print1(n", ")))}
(PARI) list(lim)=lim\=1; my(v=List(), x=2*lim+5, u=vectorsmall(x)); forprime(p=2, x\2, forprime(q=2, min(lim\p, p), u[p*q]=1)); forstep(n=15117, lim, 4, if(u[n] && u[n+1] && u[n+2] && u[2*n+1] && u[2*n+3] && u[2*n+5], listput(v, n))); Vec(v) \\ Charles R Greathouse IV, Mar 10 2017

Crossrefs

Subsequence of A056809 and of A111153. Cf. A001358.

Sequence in context: A257014 A237335 A206410 * A190294 A124047 A113008

Adjacent sequences: A283524 A283525 A283526 * A283528 A283529 A283530

Keyword

nonn

Author

Zak Seidov, Mar 09 2017

Status

approved