login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A046354 Composite palindromes whose sum of prime factors is palindromic (counted with multiplicity). 3
4, 6, 8, 9, 121, 292, 444, 575, 717, 828, 989, 1331, 2002, 4884, 5445, 8668, 9559, 10201, 11211, 11811, 13231, 14241, 14541, 14641, 15251, 15751, 16261, 16761, 18281, 19291, 19591, 20002, 21112, 21312, 22022, 22922, 23832, 26062, 26162 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. J. Mathar and Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 681 terms from R. J. Mathar)

FORMULA

A046352 INTERSECT A002113. - R. J. Mathar, Sep 09 2015

EXAMPLE

15751 = 19 * 829 -> 19 + 829 = 848 and 848 is a palindrome.

MAPLE

n := 1 ;

for i from 3 to 30000 do

    pal := A002113(i) ;

    if not isprime(pal) then

        sof := A001414(pal) ;

        if isA002113(sof) then

            printf("%d %d\n", n, pal) ;

            n := n+1 ;

        end if;

    end if;

end do: # R. J. Mathar, Sep 09 2015

MATHEMATICA

palQ[n_]:=Reverse[x=IntegerDigits[n]]==x; Select[Range[4, 26170], !PrimeQ[#]&&And@@palQ/@{#, Total[Times@@@FactorInteger[#]]}&](* Jayanta Basu, Jun 05 2013 *)

CROSSREFS

Cf. A046352, A046353.

Sequence in context: A232541 A076612 A182775 * A046357 A227947 A144123

Adjacent sequences:  A046351 A046352 A046353 * A046355 A046356 A046357

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Jun 15 1998.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 23 08:03 EDT 2017. Contains 286909 sequences.