A376472 Composite terms in A376471.
6, 9, 20, 25, 77, 81, 121, 208, 256, 323, 361, 625, 667, 841, 1147, 1369, 1763, 1849, 2303, 2401, 3127, 3481, 4087, 4489, 5183, 5329, 6557, 6561, 6889, 8633, 9409, 10403, 10609, 11663, 11881, 14351, 14641, 16129, 17947, 18769, 20711, 22201, 23707, 24649, 27221
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..204
Programs
-
Mathematica
expPow2Q[n_] := AllTrue[FactorInteger[n][[;; , 2]], # == 2^IntegerExponent[#, 2] &]; s[1] = 1; s[n_] := s[n] = Module[{prod = Times @@ Array[s, n - 1], k = s[n - 1] + 1}, While[! expPow2Q[prod*k], k++]; k]; Select[Array[s, 1000], CompositeQ] -
PARI
ispow2(n) = if(n == 0, 1, n >> valuation(n, 2) == 1); lista(pindmax) = {my(pmax = prime(pindmax), v = vector(pindmax), f, pind, prd); for(k = 2, pmax, f = factor(k); pind = apply(x -> primepi(x), f[,1]); for(i = 1, #pind, v[pind[i]] += f[i, 2]); if(vecprod(apply(x -> ispow2(x), v)) > 0, if(!isprime(k), print1(k, ", ")), for(i = 1, #pind, v[pind[i]] -= f[i, 2])));}
Comments