A337190 Numbers k such that A337183(k) and k + A337183(k) are prime.
6, 10, 22, 42, 68, 102, 106, 116, 126, 168, 170, 178, 186, 202, 230, 242, 262, 356, 366, 436, 480, 502, 506, 516, 610, 622, 630, 638, 668, 696, 716, 778, 788, 798, 868, 890, 990, 1018, 1034, 1042, 1070, 1108, 1126, 1166, 1186, 1198, 1206, 1228, 1264, 1268, 1350, 1388, 1446, 1614, 1650, 1682, 1690
Offset: 1
Examples
a(3) = 22 is a member because A337183(22) = 37 and 37+22 = 59 are both prime.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
f:= proc(n) local F, b, i; F:= sort(map(t -> t[1]$t[2], ifactors(n)[2]), `>`); b:= convert(F, `+`); (add(F[i]*b^(i-1), i=1..nops(F))); end proc: filter:= proc(n) local v; v:= f(n); isprime(v) and isprime(v+n) end proc: select(filter, 2*[$1..1000]);
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Mathematica
Select[Range[2, 1690], AllTrue[If[PrimeQ@ #, #, FromDigits[#, Total[#]] &@ Flatten[ConstantArray @@@ FactorInteger[#]]] + {0, #}, PrimeQ] &] (* Michael De Vlieger, Jan 29 2021 *)
Comments