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A342035
Numbers k such that both bigomega(k)+sopfr(k) and bigomega(k)+sopfr(k)+k are prime.
1
2, 6, 18, 24, 26, 30, 38, 56, 72, 90, 104, 120, 152, 158, 162, 174, 206, 218, 288, 294, 318, 342, 344, 350, 354, 360, 378, 408, 446, 458, 486, 510, 522, 534, 558, 690, 696, 698, 726, 776, 792, 824, 878, 894, 910, 936, 990, 992, 1016, 1056, 1078, 1098, 1152, 1170, 1184, 1256, 1278, 1286, 1330
OFFSET
1,1
COMMENTS
Numbers k such that A001222(k)+A001414(k) and A001222(k)+A001414(k)+k are prime.
All terms are even.
Semiprimes in the sequence are 2*p where p is in the intersection of A023200 and A023209.
LINKS
EXAMPLE
a(4) = 24 = 2^3*3 is in the sequence because A001222(24) = 3+1 = 4, A001414(24) = 3*2+3 = 9, and 4+9 = 13 and 4+9+24 = 37 are prime.
MAPLE
filter:= proc(n) local k, v;
v:= add(k[2]*(1+k[1]), k = ifactors(n)[2]);
isprime(v) and isprime(n+v)
end proc:
select(filter, [seq(i, i=2..2000, 2)]);
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Feb 25 2021
STATUS
approved