A098922 Reverse digits of largest primes, append to sequence if result is larger prime then previous one with reverse digits.

2, 3, 5, 7, 11, 31, 71, 73, 97, 101, 701, 941, 971, 991, 9001, 9601, 9721, 9931, 9941, 9967, 70001, 90001, 93001, 96001, 97001, 99401, 99611, 99721, 99881, 99923, 99989, 940001, 972001, 973001, 996001, 997001, 999101, 999331, 999431, 999631, 999931

Offset: 1

Author

Jani Melik, Oct 18 2004

Keywords

• base
• easy
• nonn

Examples

			The prime 37 in reverse is 73. 73 is prime and is larger than previous prime (17), written with reverse digits 71.
		

Crossrefs

Cf. A004087, A095180.

Programs

Maple

obrni_stev:=proc(n) local i, tren, tren1, st, ans; ans:=[ ]: tren:=n: tren1:=0: for i while (tren>0) do st:=round( 10*frac(tren/10) ): ans:=[ op(ans), st ]: tren:=trunc(tren/10): od; for i from 0 to nops(ans)-1 do tren1:= tren1 + op(nops(ans)-i, ans)*10^(i); od: RETURN(tren1); end: ts_inv_prav_pra:= proc(n) local i, tren, ans; tren:=0: ans:=[ ]: for i from 1 to n do if ( isprime( i ) = 'true' and isprime( obrni_stev (i) )='true' and obrni_stev(i) > tren ) then ans:=[ op(ans),obrni_stev(i) ]; tren:=obrni_stev(i); fi: od: RETURN(ans); end: ts_inv_prav_pra(200000);