OFFSET
1,2
COMMENTS
The numbers of terms not exceeding 10^k, for k = 1, 2, ..., are 8, 78, 762, 7615, 76113, 761127, 7611222, 76111895, 761119135, 7611190807, ... . Apparently, the asymptotic density of this sequence exists and equals 0.761119... .
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
expOdQ[n_] := AllTrue[FactorInteger[n][[;; , 2]], OddQ[DigitCount[#, 2, 1]] &]; Select[Range[100], And @@ expOdQ /@ {#, # + 1} &]
PROG
(PARI) isexpod(n) = {my(f = factor(n)); for(i=1, #f~, if (!(hammingweight(f[i, 2]) % 2), return (0))); 1; }
is(n) = isexpod(n) && isexpod(n+1)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amiram Eldar, Nov 27 2023
STATUS
approved