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A364937 a(n) is the least prime p such that p - prime(n) and p + prime(n) are triprimes. 1
173, 47, 13, 37, 19, 31, 59, 31, 43, 37, 61, 79, 61, 71, 67, 61, 71, 103, 97, 83, 101, 107, 103, 97, 139, 167, 179, 137, 127, 131, 139, 151, 149, 151, 167, 181, 199, 191, 269, 181, 191, 193, 211, 211, 239, 211, 223, 251, 271, 241, 241, 269, 283, 353, 277, 271, 313, 347, 401, 293, 313, 311, 409 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
a(3) = 13 because prime(3) = 5 and 13 - 5 = 8 = 2^3 and 13 + 5 = 18 = 2*3^2 are triprimes.
MAPLE
f:= proc(n) local p, q;
q:= ithprime(n); p:= q;
do
p:= nextprime(p);
if numtheory:-bigomega(p-q) = 3 and numtheory:-bigomega(p+q) = 3 then return p fi;
od
end proc;
map(f, [$1..100]);
MATHEMATICA
s={}; p=1; Do[p=NextPrime[p]; q=NextPrime[p]; While[3!= PrimeOmega[q+p]||3!=
PrimeOmega[q-p], q=NextPrime[q]]; AppendTo[s, q], {100}];
CROSSREFS
Cf. A014612.
Sequence in context: A035828 A259017 A097845 * A261530 A246135 A140002
KEYWORD
nonn
AUTHOR
Zak Seidov and Robert Israel, Aug 13 2023
STATUS
approved

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Last modified June 23 11:52 EDT 2024. Contains 373648 sequences. (Running on oeis4.)