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A283527 First of three consecutive Sophie Germain semiprimes: n, n+1 and n+2 are all terms of A111153. 1
15117, 17245, 34413, 93453, 143101, 157713, 190621, 208293, 233097, 294301, 323281, 346497, 470341, 501477, 1306113, 1337221, 1346401, 1655853, 1682313, 1774801, 1877613, 1879021, 1933233, 1976041 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 17 19:10 EDT 2019. Contains 324198 sequences. (Running on oeis4.)