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A046355 Composite numbers with only palindromic prime factors whose sum is palindromic (counted with multiplicity). 5

%I #18 Oct 10 2019 22:53:06

%S 4,6,8,9,10,12,14,15,16,18,20,24,27,28,40,45,48,54,121,308,440,495,

%T 528,594,735,784,875,882,1050,1120,1250,1260,1331,1344,1500,1512,1600,

%U 1701,1800,1920,2025,2048,2101,2121,2160,2304,2430,2525,2592,2751,2916,3030

%N Composite numbers with only palindromic prime factors whose sum is palindromic (counted with multiplicity).

%C Subsequence of the numbers k in A046349 such that A262049(k) is in A002113. - _R. J. Mathar_, Sep 09 2015

%H Giovanni Resta, <a href="/A046355/b046355.txt">Table of n, a(n) for n = 1..10000</a>

%e 3030 = 2 * 3 * 5 * 101 -> 2 + 3 + 5 + 101 = 111 and 111 is a palindrome.

%p isA046355 := proc(n)

%p local sofpp ;

%p if isA046349(n) then

%p sofpp := A262049(n) ;

%p isA002113(sofpp) ;

%p else

%p false;

%p end if;

%p end proc:

%p for n from 2 to 400 do

%p if isA046355(n) then

%p printf("%d,",n);

%p end if;

%p end do: # _R. J. Mathar_, Sep 09 2015

%t palQ[n_] := Reverse[x=IntegerDigits[n]] == x; Select[Range[4,3100], !PrimeQ[#] && And@@palQ/@Join[{Total[Times@@@(x=FactorInteger[#])]}, First/@x]&] (* _Jayanta Basu_, Jun 05 2013 *)

%Y Cf. A046356, A046357.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jun 15 1998

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Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)