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A079150

Primes p such that p+1 has at most 3 prime factors, counted with multiplicity; i.e., primes p such that bigomega(p+1) = A001222(p+1) <= 3.

2, 3, 5, 7, 11, 13, 17, 19, 29, 37, 41, 43, 61, 67, 73, 97, 101, 109, 113, 137, 157, 163, 173, 181, 193, 211, 229, 241, 257, 277, 281, 283, 313, 317, 331, 337, 353, 373, 397, 401, 409, 421, 433, 457, 523, 541, 547, 577, 601, 613, 617, 641, 653, 661, 673, 677

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OFFSET

1,1

LINKS

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

EXAMPLE

173 is in the sequence because 173+1 = 2*3*29 has 3 prime factors.

MATHEMATICA

Select[Prime[Range[200]], PrimeOmega[#+1]<4&] (* Harvey P. Dale, Feb 02 2012 *)

PROG

(PARI) s(n) = {sr=0; ct=0; forprime(x=2, n, if(bigomega(x+1) < 4, print1(x" "); sr+=1.0/x; ct+=1; ); ); print(); print(ct" "sr); } \\ Lists primes p<=n such that p+1 has at most 3 prime factors.

CROSSREFS

Cf. A001222, A079147, A079151, A079152, A079153.

Sequence in context: A385856 A061771 A124589 * A177000 A117843 A293667

Adjacent sequences: A079147 A079148 A079149 * A079151 A079152 A079153

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Dec 27 2002

STATUS

approved

URL: https://oeis.org/A079150

⇱ A079150 - OEIS