A108662 Numbers whose sum of squares of digits is a prime.

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

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: A227823 A332379 A140353 * A210767 A182404 A234021

Adjacent sequences: A108659 A108660 A108661 * A108663 A108664 A108665

Keyword

nonn,base

Author

Zak Seidov, Jun 16 2005

Status

approved