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 A224164 Prime numbers with m^2 digits that, if arranged in an m X m matrix, form m-digit reversible primes in each row, column, and main diagonal. 2
 2, 3, 5, 7, 1117, 1171, 7331, 131983991, 179907191, 179991179, 191199311, 191739971, 191797919, 199199311, 199709971, 199937971, 337353739, 373151113, 733353337, 797389337, 919311739, 971727179, 1193100992213191, 1193120192093911, 1193123793413719 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Number of primes with m^2 digits in this sequence are 4, 3, 15, 86, ... Smallest primes with m^2 digits in this sequence are 2, 1117, 131983991, 1193100992213191, ... Largest primes with m^2 digits in this sequence are 7, 7331, 971727179, 9931722992931193, ... Palindromic primes in this sequence are 2, 3, 5, 7, 733353337, 971727179, ... There are 1303816 terms with 25 digits, from 1119710007309831033317939 to 9979399989793939049937997, while the terms with 36 digits range from 111119100049100049150607134777979313 to 999931999983999983792293733331319919. - Giovanni Resta, Apr 05 2013 REFERENCES Chris K. Caldwell; G. L. Honaker, Jr.: Prime Curios! The Dictionary of Prime Number Trivia. CreateSpace 2009, p. 219, and 229. LINKS Martin Renner and Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 108 terms from Martin Renner) Chris K. Caldwell and G. L. Honaker, Jr., Prime Curios! 733353337. Chris K. Caldwell and G. L. Honaker, Jr., Prime Curios! 3391382115599173. Chris K. Caldwell and G. L. Honaker, Jr., Prime Curios! 19973...37991 (25-digits). EXAMPLE a(5) = 1117 is the smallest 4-digit prime, that if arranged in a 2 X 2 matrix yields to each row, column, and main diagonal being prime in both directions, i. e.   11   17 -> 11 (4 times), 17 (3 times), 71 (3 times) are all reversible primes. a(8) = 131983991 is the smallest 9-digit prime, that if arranged in a 3 X 3 matrix yields to each row, column, and main diagonal being prime in both directions, i. e.   131   983   991 -> 131 (4 times), 181, 199, 389, 983, 991 (each 2 times) are all reversible primes. a(23) = 1193100992213191 is the smallest 16-digit prime, that if arranged in a 4 X 4 matrix yields to each row, column, and main diagonal being prime in both directions, i. e.   1193   1009   9221   3191 -> 1009, 1021 (2 times), 1193 (3 times), 1201 (2 times), 1229, 1913, 3191, 3911 (3 times), 9001, 9029, 9209, 9221 are all reversible primes. MAPLE # Maple-program generating all 4-digit primes M:={}: for a in [1, 3, 7, 9] do for b in [1, 3, 7, 9] do if isprime(10*a+b) and isprime(10*b+a) then for c in [1, 3, 7, 9] do for d in [1, 3, 7, 9] do if isprime(10*c+d) and isprime(10*d+c) and isprime(10*a+c) and isprime(10*c+a) and isprime(10*b+d) and isprime(10*d+b) and isprime(10*a+d) and isprime(10*d+a) then S:=[a, b, c, d]: if isprime(add(S[j]*10^(4-j), j=1..4)) then M:={op(M), add(S[j]*10^(4-j), j=1..4)}: fi: fi: od: od: fi: od: od: M; # Maple-program generating all 9-digit primes M:={}: for d in [1, 3, 7, 9] do for e from 0 to 9 do for f in [1, 3, 7, 9] do if isprime(100*d+10*e+f) and isprime(100*f+10*e+d) then for a in [1, 3, 7, 9] do for b in [1, 3, 7, 9] do for c in [1, 3, 7, 9] do if isprime(100*a+10*b+c) and isprime(100*c+10*b+a) then for g in [1, 3, 7, 9] do for h in [1, 3, 7, 9] do for i in [1, 3, 7, 9] do if isprime(100*g+10*h+i) and isprime(100*i+10*h+g) and isprime(100*a+10*d+g) and isprime(100*g+10*d+a) and isprime(100*b+10*e+h) and isprime(100*h+10*e+b) and isprime(100*c+10*f+i) and isprime(100*i+10*f+c) and isprime(100*a+10*e+i) and isprime(100*i+10*e+a) then S:=[a, b, c, d, e, f, g, h, i]: if isprime(add(S[j]*10^(9-j), j=1..9)) then M:={op(M), add(S[j]*10^(9-j), j=1..9)}: fi: fi: od: od: od: fi: od: od: od: fi: od: od: od: M; CROSSREFS Cf. A224398. Sequence in context: A109208 A050665 A090721 * A224398 A066306 A212667 Adjacent sequences:  A224161 A224162 A224163 * A224165 A224166 A224167 KEYWORD nonn,base AUTHOR Martin Renner, Mar 31 2013 STATUS approved

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Last modified November 27 12:03 EST 2021. Contains 349394 sequences. (Running on oeis4.)