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A134462
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Centered decagonal palindromic primes; or palindromic primes of the form 5k^2 + 5k + 1.
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2
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OFFSET
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1,1
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COMMENTS
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Sequence is the intersection of the palindromic primes = A002385 = {2, 3, 5, 7, 11, 101, 131, 151, ...} and the centered 10-gonal numbers = A062786 = {1, 11, 31, 61, 101, 151, ...}. Corresponding numbers k such that 5k^2 + 5k + 1 is a term of A134462 are listed in A134463 = {1, 4, 5, 565, 475081, ...}. Note that the first 4 terms of A134463 are palindromic as well.
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LINKS
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MATHEMATICA
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Do[ f=5k^2+5k+1; If[ PrimeQ[f] && FromDigits[ Reverse[ IntegerDigits[ f ] ] ] == f, Print[ f ] ], {k, 1, 500000} ]
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CROSSREFS
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Cf. A062786 = Centered 10-gonal numbers.
Cf. A090562 = Primes of the form 5k^2 + 5k + 1.
Cf. A090563 = Values of k such that 5k^2 + 5k + 1 is a prime.
Cf. A134463 = Values of k such that 5k^2 + 5k + 1 is a palindromic prime.
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KEYWORD
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more,nonn,base
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AUTHOR
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EXTENSIONS
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More terms from Tomas J. Bulka (tbulka(AT)rodincoil.com), Aug 30 2009
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STATUS
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approved
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