A048525 Primes for which only three iterations of 'Prime plus its digit sum equals a prime' are possible.

277, 1559, 5779, 7489, 11279, 15091, 22093, 37811, 43579, 46279, 48541, 49957, 53479, 54751, 60589, 68473, 72883, 74821, 83621, 85621, 90793, 91921, 93901, 97501, 107981, 110899, 111799, 120193, 153379, 157739, 170299, 180731, 184441

Offset: 1

Author

Patrick De Geest, May 15 1999

Keywords

• nonn
• base

Examples

			prime 7489 -> 7489 + (7+4+8+9) = prime 7517 -> 7517 + (7+5+1+7) = prime 7537 -> 7537 + (7+5+3+7) = prime 7559 -> next iteration yields composite 7585.
		

Links

• Lars Blomberg, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A047791, A048519.

Programs

Mathematica

tiQ[p_]:=Boole[PrimeQ[NestList[#+Total[IntegerDigits[#]]&,p,4]]]=={1,1,1,1,0}; Select[Prime[Range[20000]],tiQ] (* Harvey P. Dale, Dec 02 2024 *)