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A083526 Composite n such that both n and its reversal in base 10 are squarefree, none of the prime factors of n are palindromes and the prime factors of the reversal of n are the reversals of those of n. 0
1469, 9641, 13273, 14339, 15613, 15769, 15899, 16913, 31651, 31961, 34193, 37231, 39143, 39299, 93341, 96751, 99293, 99851, 115373, 124639, 135713, 143039, 157469, 159913, 317531, 319951, 341093, 373511, 390143, 392899, 930341, 936421, 964751 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Many trivial terms are obtained if one drops the requirement that none of the prime factors of n be palindromes.
If n is in the sequence, so is its reversal. The smallest palindrome in the sequence is 1226221 = 1021 * 1201.
All terms up to 5000000 have just 2 prime factors and the digits of the prime factors are all 0, 1, 2, or 3. Is this true for all terms?
LINKS
EXAMPLE
1469 is the product of two distinct non-palindromic primes: 1469 = 13 * 113 and reverse(1469) = 9641 has prime factorization 9641 = reverse(13) * reverse(113) = 31 * 311. Hence 1469 belongs to the sequence.
MATHEMATICA
rev[n_] := FromDigits[Reverse[IntegerDigits[n]]]; pal[n_] := n==rev[n]; For[n=2, True, n++, ps=First/@(fn=FactorInteger[n]); If[Length[fn]>1&&Max@@Last/@fn==1&&!Or@@pal/@ps&&And@@PrimeQ/@rev/@ps&&Times@@rev/@ps==rev[n], Print[n]]];
CROSSREFS
Sequence in context: A215849 A204871 A252578 * A068753 A255735 A252521
KEYWORD
nonn,base
AUTHOR
Joseph L. Pe, Jun 09 2003
EXTENSIONS
Edited by Dean Hickerson, Jun 12 2003
STATUS
approved

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Last modified March 19 02:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)