

A108662


Numbers whose sum of squares of digits is a prime.


7



11, 12, 14, 16, 21, 23, 25, 27, 32, 38, 41, 45, 49, 52, 54, 56, 58, 61, 65, 72, 78, 83, 85, 87, 94, 101, 102, 104, 106, 110, 111, 113, 119, 120, 126, 131, 133, 137, 140, 146, 159, 160, 162, 164, 166, 168, 173, 179, 186, 191, 195, 197, 199, 201, 203, 205, 207, 210
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

If m is in the sequence, then so are 10*m and any anagram (even with adding zeros between digits) of m. E.g., 12 is a term, hence 21, 102, 120, 201, 10020 all are here.
A sequence of primitive terms is of interest. It starts with 11, 12, 14, 16, 23, 25, 27, 38, 45, 49, 56, 58, 78, 111, 113, 119, 126, 133, 137, 146, 159, 166, 168, 179, 199. Note that digits are in nondecreasing order.  Zak Seidov, Dec 31 2013


LINKS

Harvey Dale and Zak Seidov, Table of n, a(n) for n = 1..10000 [First 1000 terms from Harvey Dale]


EXAMPLE

23 is in the sequence because 2^2 + 3^2 = 13 is a prime.


MATHEMATICA

Select[Range[300], PrimeQ[Total[IntegerDigits[#]^2]]&] (* Harvey P. Dale, May 25 2012 *)


PROG

(PARI) isok(n) = isprime(norml2(digits(n))); \\ Michel Marcus, Jan 09 2019


CROSSREFS

Cf. A003132, A009994, A052034, A234021.
Sequence in context: A221699 A227823 A140353 * A210767 A182404 A234021
Adjacent sequences: A108659 A108660 A108661 * A108663 A108664 A108665


KEYWORD

nonn,base


AUTHOR

Zak Seidov, Jun 16 2005


STATUS

approved



