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 A084983 Palindromes made of only prime digits. 1
 2, 3, 5, 7, 22, 33, 55, 77, 222, 232, 252, 272, 323, 333, 353, 373, 525, 535, 555, 575, 727, 737, 757, 777, 2222, 2332, 2552, 2772, 3223, 3333, 3553, 3773, 5225, 5335, 5555, 5775, 7227, 7337, 7557, 7777, 22222, 22322, 22522, 22722, 23232, 23332, 23532, 23732, 25252, 25352 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Andrew Howroyd, Table of n, a(n) for n = 1..1000 MATHEMATICA With[{p = Prime@ Range@ PrimePi@ 9}, Array[If[OddQ@ #1, Map[FromDigits@ Join[#, Reverse@ Most@ #] &, #2], Map[FromDigits@ Join[#, Reverse@ #] &, #2]] & @@ {#, Tuples[p, {Ceiling[#/2]}]} &, 5]] // Flatten (* Michael De Vlieger, Jan 28 2020 *) PROG (PARI) a(n)={my(k=4); while(n>2*k, n-=2*k; k*=4); my(v=[d*2+1+(!d)|d<-digits(k+n-1, 4)]); fromdigits(concat(v[2..#v-(n<=k)], Vecrev(v[2..#v])))} \\ Andrew Howroyd, Jan 27 2020 CROSSREFS Intersection of A002113 and A046034. Sequence in context: A046034 A062087 A162457 * A062239 A066483 A114420 Adjacent sequences:  A084980 A084981 A084982 * A084984 A084985 A084986 KEYWORD nonn,base AUTHOR Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 27 2003 EXTENSIONS Terms a(33) and beyond from Andrew Howroyd, Jan 27 2020 STATUS approved

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Last modified November 24 22:57 EST 2020. Contains 338616 sequences. (Running on oeis4.)