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A235646
Primes p such that b=2*p+1 is semiprime, c=2*b+1 is 3-almost prime and d=2*c+1 is 4-almost prime.
1
43, 1429, 2239, 3319, 4831, 6379, 8821, 10501, 11383, 12781, 13003, 14771, 15091, 16063, 16759, 18223, 19213, 19681, 20021, 22571, 24103, 24109, 24571, 25939, 27271, 28933, 29833, 30241, 31723, 33679, 33811, 34381, 34781, 35591, 35863, 39373
OFFSET
1,1
LINKS
EXAMPLE
p = 43, b = 87 = 2*29 = A001358(30), c = 175 = 5*5*7 = A014612(43), d = 351 = 3*3*3**13 = A014613(50).
MATHEMATICA
Select[ Prime@ Range@ 4200, PrimeOmega[2#+1]==2 && PrimeOmega[4#+3]==3 && PrimeOmega[8#+7]==4 &] (* Robert G. Wilson v, Feb 22 2014 *)
PROG
(PARI) forprime(p=43, 40000, if(bigomega(a=2*p+1)==2&& bigomega(b=2*c+1)==3&&bigomega(c=2*d+1)==4, print(p", ")))
CROSSREFS
Subsequence of A238202.
Sequence in context: A229432 A122575 A014938 * A022220 A297028 A198206
KEYWORD
nonn
AUTHOR
Zak Seidov, Feb 20 2014
STATUS
approved