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A117985 Pentagonal numbers with only odd digits. 2

%I #9 Oct 17 2021 13:31:33

%S 1,5,35,51,117,715,1335,1717,3151,3577,5551,5735,7315,7957,15555,

%T 55777,71177,73151,99717,135751,171197,319935,331115,335357,371757,

%U 377755,711737,755795,935755,1111551,1517551,1553977,1739355,1911397,1993537,3131315,3311551

%N Pentagonal numbers with only odd digits.

%H Harvey P. Dale, <a href="/A117985/b117985.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Table[n*(3*n - 1)/2, {n, 0, 3000}], AllTrue[IntegerDigits[#], OddQ] &] (* _Amiram Eldar_, Feb 06 2021 *)

%t Select[PolygonalNumber[5,Range[1500]],AllTrue[IntegerDigits[#],OddQ]&] (* _Harvey P. Dale_, Oct 17 2021 *)

%Y Intersection of A000326 and A014261.

%Y Cf. A117990.

%K base,nonn

%O 1,2

%A Luc Stevens (lms022(AT)yahoo.com), May 03 2006

%E Missing terms inserted by _Amiram Eldar_, Feb 06 2021

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)