A139749 Numbers n such that d_1^r + ... + d_r^1 is a prime number, where d_i are the digits of n (n = d_1, ..., d_r).

2, 3, 5, 7, 11, 12, 14, 16, 21, 23, 27, 29, 32, 34, 38, 41, 43, 47, 54, 56, 61, 65, 67, 74, 83, 87, 89, 92, 98, 101, 102, 104, 106, 110, 111, 113, 115, 119, 120, 122, 126, 128, 131, 133, 137, 139, 140, 142, 146, 153, 155, 160, 164, 166, 173, 179, 182, 186, 188, 191

Offset

1,1

Links

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

Example

1^3 + 3^2 + 7^1 = 17 is prime. Thus 137 is a member of this sequence. - Derek Orr, Jul 13 2014

Mathematica

Select[Range[200], PrimeQ[Total[IntegerDigits[#]^Range[IntegerLength[#], 1, -1]]]&] (* Harvey P. Dale, Aug 14 2019 *)

Prog

(PARI) for(n=1, 10^3, d=digits(n); s=sum(i=1, #d, d[i]^(#d-i+1)); if(isprime(s), print1(n, ", "))) \\ Derek Orr, Jul 13 2014

Crossrefs

Cf. A139751.

Sequence in context: A070026 A139750 A330125 * A178357 A205667 A241506

Adjacent sequences: A139746 A139747 A139748 * A139750 A139751 A139752

Keyword

base,easy,nonn,less

Author

Ctibor O. Zizka, May 19 2008

Extensions

Edited and extended by Klaus Brockhaus, May 21 2008

Status

approved