A339438 Composite numbers k such that k + A339436(k) is prime.
6, 10, 14, 15, 20, 21, 24, 26, 33, 34, 35, 38, 40, 44, 46, 51, 52, 55, 57, 58, 63, 65, 74, 76, 85, 86, 88, 90, 92, 93, 96, 111, 117, 118, 123, 124, 135, 136, 141, 143, 145, 147, 150, 153, 155, 158, 161, 164, 166, 172, 177, 178, 180, 184, 185, 194, 198, 201, 203, 205, 206, 207, 208, 209, 215, 221
Offset: 1
Keywords
Examples
a(5)=20 is a term because 20=2*2*5 and 2+2*2+2*2*5+2*5+5 = 41 is prime.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
filter:= proc(n) local L,m; L:= sort(map(t -> t[1]$t[2],ifactors(n)[2])); m:= nops(L); if m=1 then return false fi; isprime(n + add(mul(L[i],i=1..j)+mul(L[i],i=j+1..m),j=1..m-1)) end proc: select(filter, [$4..300]);
Comments