A180006 Composite numbers that can be obtained from primes by interchanging the first and last digits.

91, 32, 92, 14, 34, 74, 35, 95, 16, 76, 38, 98, 301, 901, 721, 731, 931, 361, 371, 391, 791, 112, 322, 722, 922, 332, 932, 142, 152, 752, 362, 962, 172, 772, 182, 382, 392, 703, 713, 133, 943, 763, 973, 793, 104, 904, 914, 124, 134, 334, 934, 344, 944, 754

Offset: 1

Author

Parthasarathy Nambi, Aug 06 2010

Keywords

• nonn
• base

Comments

The primes must contain at least two digits.

Examples

			The composite number 752 is obtained from the prime 257 by interchanging the first and last digits.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

The corresponding primes are A076056. Cf. A002808, A179826.

Programs

Mathematica

Select[With[{idn=IntegerDigits[#]},FromDigits[Join[{idn[[-1]]},Most[Rest[idn]],{idn[[1]]}]]]&/@Prime[Range[5,1500]],CompositeQ] (* Harvey P. Dale, Jan 26 2025 *)

Extensions

More terms from Vincenzo Librandi, Aug 06 2010