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 A230820 Table, read by antidiagonals, of palindromic primes in base b expressed in decimal. 2
 3, 2, 5, 2, 13, 7, 2, 3, 23, 17, 2, 3, 5, 151, 31, 2, 3, 31, 17, 173, 73, 2, 3, 5, 41, 29, 233, 107, 2, 3, 5, 7, 67, 59, 757, 127, 2, 3, 5, 71, 37, 83, 257, 937, 257, 2, 3, 5, 7, 107, 43, 109, 373, 1093, 313, 2, 3, 5, 7, 73, 157, 61, 701, 409, 1249, 443 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE \r b\ .2.3...5...7...17...31...73..107..127...257...313...443..1193..1453..1571.=A016041 .3.2..13..23..151..173..233..757..937..1093..1249..1429..1487..1667..1733.=A029971 .4.2...3...5...17...29...59..257..373...409...461...509...787...839...887.=A029972 .5.2...3..31...41...67...83..109..701...911..1091..1171..1277..1327..1667.=A029973 .6.2...3...5....7...37...43...61...67...191...197..1297..1627..1663..1699.=A029974 .7.2...3...5...71..107..157..257..271...307..2549..2647..2801..3347..3697.=A029975 .8.2...3...5....7...73...89...97..113...211...227...251...349...373...463.=A029976 .9.2...3...5....7..109..127..173..191...227...337...373...419...601...619.=A029977 10.2...3...5....7...11..101..131..151...181...191...313...353...373...383.=A002385 11.2...3...5....7..199..277..421..443...499...521...587...643...709...743.=A029978 12.2...3...5....7...11...13..157..181...193...229...241...277...761...773.=A029979 ... inf..2..3..5..7..11..13..17..19..23..29..31..37..41..43..47..53..59..61...=A000040 MAPLE A230820 := proc(b, n)     option remember;     local a, dgs ;     if n = 1 then         if b = 2 then             return 3;         else             return 2;         end if;     else         for a from procname(b, n-1)+1 do             if isprime(a) then                 ispal := true ;                 dgs := convert(a, base, b) ;                 for i from 1 to nops(dgs)/2 do                     if op(i, dgs) <> op(-i, dgs) then                         ispal := false;                     end if;                 end do:                 if ispal then                     return a;                 end if;             end if;         end do:     end if; end proc: for b from 2 to 9 do     for n from 1 to 9 do         printf("%3d ", A230820(b, n)) ;     end do:     printf("\n") ; end do; # R. J. Mathar, Feb 16 2014 MATHEMATICA palQ[n_Integer, base_Integer] := Module[{idn = IntegerDigits[ n, base]}, idn == Reverse@ idn]; Table[Select[Prime@Range@500, palQ[#, k + 1] &][[b - k + 1]], {b, 11}, {k, b, 1, -1}] // Flatten CROSSREFS Cf. A000040, A016041, A029971, A029972, A029973, A029974, A029975, A029976, A029977, A002385, A029978, A029979, A029980, A029981, A029982, A029732, A182231. Sequence in context: A046227 A120842 A319044 * A324549 A152178 A274164 Adjacent sequences:  A230817 A230818 A230819 * A230821 A230822 A230823 KEYWORD nonn,base,easy,tabl AUTHOR Robert G. Wilson v, Oct 30 2013 STATUS approved

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Last modified May 16 04:58 EDT 2022. Contains 353690 sequences. (Running on oeis4.)