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A374331
Palindromic squarefree semiprimes such that the sum of the two prime factors is also a palindrome.
0
6, 717, 989, 13231, 15251, 15751, 18281, 19291, 31613, 34043, 35653, 37073, 37673, 38383, 38683, 97079, 98789, 99899, 1115111, 1226221, 1794971, 3525253, 3755573, 3782873, 104646401, 114202411, 127888721, 133707331, 134010431, 137181731, 138050831, 146828641, 157494751, 157585751, 161555161
OFFSET
1,1
EXAMPLE
717 is a term because 717 = 3*239 and 3 + 239 = 242.
MATHEMATICA
Select[Range[10^6], PalindromeQ[#] && SquareFreeQ[#] && PrimeNu[#]==2 && PalindromeQ[Total[First/@FactorInteger[#]]]&] (* Stefano Spezia, Jul 06 2024 *)
PROG
(PARI) ispal(n)=my(d=digits(n)); d==Vecrev(d) \\
for(a=2, 10^10, if(omega(a)==2&&bigomega(a)==2 &&ispal(a), b=factor(a)[1, 1]+factor(a)[2, 1]; if(ispal(b), print1(a, ", "))))
(PARI) isok(k) = if (issquarefree(k) && ispal(k), my(f=factor(k)); (bigomega(f)==2) && ispal(f[1, 1]+f[2, 1])); \\ Michel Marcus, Jul 05 2024
CROSSREFS
Sequence in context: A354250 A218559 A201391 * A289367 A014525 A289747
KEYWORD
nonn,base
AUTHOR
Alexandru Petrescu, Jul 05 2024
STATUS
approved