A343706 Lesser emirps (A109308) p such that A056964(p) is in A343703.

17, 107, 113, 167, 179, 389, 1031, 1091, 1097, 1109, 1181, 1259, 1439, 1487, 1523, 1583, 1619, 1847, 3023, 3089, 3257, 3347, 3359, 3527, 3719, 7349, 7529, 7577, 7589, 7649, 7949, 9029, 10067, 10151, 10247, 10487, 10739, 10781, 11057, 11423, 11621, 11777, 11897, 11933, 12119, 12227, 12641, 13151

Offset

1,1

Comments

Primes p such that the digit-reversal q = A004086(p) is a prime greater than p, and p+q = x*y for some x and y such that x+y and the concatenation x|y are primes.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Carlos Rivera, Puzzle 1036. P + R(p) such that..., The Prime Puzzles and Problems Connection.

Example

a(4) = 167 is a term because 167 and 761 are primes with 167 < 761, and 167+761 = 928 = 32*29 with 3229 and 32+29 = 61 prime.

Maple

revdigs:= proc(n) local L, i;
    L:= convert(n, base, 10);
    add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
filter:= proc(p) local q, m, d, e;
   q:= revdigs(p); if q <= p then return false fi;
   if not isprime(p) or not isprime(q) then return false fi;
   m:= p+q;
   for d in numtheory:-divisors(m) do
     e:= m/d;
     if isprime(d*10^(1+ilog10(e))+e) and isprime(d+e) then return true fi
   od;
   false
end proc:

Crossrefs

Cf. A004086, A056964, A109308, A343703.

Sequence in context: A221938 A121823 A268263 * A282323 A224322 A142321

Adjacent sequences: A343703 A343704 A343705 * A343707 A343708 A343709

Keyword

nonn,base

Author

J. M. Bergot and Robert Israel, Apr 26 2021

Status

approved