login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Binary palindromic numbers whose digit sum and aliquot sum are also binary palindromic.
1

%I #14 Sep 26 2023 17:49:15

%S 1,3,5,7,45,313,403,1501,1619,2193,2661,5349,11997,21477,21653,24029,

%T 27499,81017,98563,104147,116423,251823,269761,284881,288049,320057,

%U 337189,344037,368077,400067,410899,413779,428683,440171,475159,523007,678309,823059

%N Binary palindromic numbers whose digit sum and aliquot sum are also binary palindromic.

%H Michael S. Branicky, <a href="/A363965/b363965.txt">Table of n, a(n) for n = 1..10000</a>

%e 45 is a term since 45 = 101101_2, A007953(45) = 4+5 = 9 = 1001_2, A001065(45) = 33 = 100001_2, and all of those binary expansions are palindromes.

%t binPalQ[n_] := PalindromeQ[IntegerDigits[n, 2]]; Select[Range[10^6], AllTrue[{#, Plus @@ IntegerDigits[#], DivisorSigma[1, #] - #}, binPalQ] &] (* _Amiram Eldar_, Jul 28 2023 *)

%o (Python)

%o from sympy import divisor_sigma as s1

%o def bp(n): return (b:=bin(n)[2:])==b[::-1]

%o def ok(n): return n and bp(n) and bp(sum(map(int,str(n)))) and bp(s1(n)-n)

%o print([k for k in range(10**6) if ok(k)]) # _Michael S. Branicky_, Jul 24 2023

%Y Subsequence of A006995.

%Y Cf. A001065, A007088, A007953.

%K nonn,base

%O 1,2

%A _Aakash Gautam_, Jul 12 2023

%E a(6) and beyond from _Michael S. Branicky_, Jul 24 2023