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 A280997 Primes that have exactly 3 ones in both their binary and ternary expansions. 1
 13, 37, 41, 67, 97, 131, 193, 577, 1033, 1153, 2053, 4129, 8209, 18433, 32771, 32801, 32833, 65539, 133121, 525313, 557057, 1049089, 4194433, 167772161, 268435459 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sequence is likely to be finite. If it exists, a(26) > 10^200. - Robert Israel, Jan 12 2017 LINKS EXAMPLE 37 is in the sequence because it is a prime and its binary expansion 100101 and ternary expansion 1101 both have exactly 3 ones. 131 is in the sequence because it is a prime and its binary expansion 10000011 and ternary expansion 11212 both have exactly 3 ones. MAPLE A:= NULL: for a from 2 to 100 do   for b from 1 to a-1 do     p:= 2^a + 2^b + 1;     if numboccur(1, convert(p, base, 3)) = 3 and isprime(p) then       A:= A, p     fi od od: A; # Robert Israel, Jan 12 2017 MATHEMATICA Select[Prime[Range[500000]], Count[IntegerDigits[#, 3], 1] == Count[IntegerDigits[#, 2], 1] == 3 &] CROSSREFS Cf. A000040, A001363, A007088, A014311, A066196. Subset of A281004. Sequence in context: A301591 A301857 A220462 * A185006 A285887 A063913 Adjacent sequences:  A280994 A280995 A280996 * A280998 A280999 A281000 KEYWORD nonn,base AUTHOR K. D. Bajpai, Jan 12 2017 STATUS approved

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Last modified May 13 23:41 EDT 2021. Contains 343868 sequences. (Running on oeis4.)