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 A318206 Numbers having no divisor d > 1 that is a binary palindrome (i.e., an element of A006995). 0
 1, 2, 4, 8, 11, 13, 16, 19, 22, 23, 26, 29, 32, 37, 38, 41, 43, 44, 46, 47, 52, 53, 58, 59, 61, 64, 67, 71, 74, 76, 79, 82, 83, 86, 88, 89, 92, 94, 97, 101, 103, 104, 106, 109, 113, 116, 118, 121, 122, 128, 131, 134, 137, 139, 142, 143, 148, 149, 151, 152, 157 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE The nonunit divisors of 22 are 2,11,22 and none of these are binary palindromes. MAPLE dmax:= 10: # to get all terms with at most dmax binary digits N:= 2^dmax-1: revdigs:= proc(n) local L, Ln, i; L:= convert(n, base, 2); Ln:= nops(L); add(L[i]*2^(Ln-i), i=1..Ln); end proc: P:= {}: for d from 2 to dmax do if d::even then P:= P union {seq(2^(d/2)*x + revdigs(x), x=2^(d/2-1)..2^(d/2)-1)} else m:= (d-1)/2; B:={seq(2^(m+1)*x + revdigs(x), x=2^(m-1)..2^m-1)}; P:= P union B union map(`+`, B, 2^m) fi od: L:= Vector(N, 1): for t in P do L[[seq(k, k=t..N, t)]]:= 0 od: select(t -> L[t]=1, [\$1..N]); # Robert Israel, Aug 21 2018 PROG (PARI) isok(n) = #select(x->((binary(x) == Vecrev(binary(x))) && (x>1)), divisors(n)) == 0; \\ Michel Marcus, Aug 21 2018 CROSSREFS Cf. A006995. Sequence in context: A236206 A078649 A161607 * A022442 A308163 A056689 Adjacent sequences: A318203 A318204 A318205 * A318207 A318208 A318209 KEYWORD nonn,base AUTHOR Jeffrey Shallit, Aug 21 2018 STATUS approved

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Last modified March 23 03:11 EDT 2023. Contains 361434 sequences. (Running on oeis4.)