cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A226802 Primes p where the digital sum of p^2 is equal to 10.

Original entry on oeis.org

19, 71, 179, 251, 449, 20249, 24499, 100549
Offset: 1

Views

Author

Vincenzo Librandi, Jun 24 2013

Keywords

Comments

The next term is > 24154957 (if it exists). - R. J. Mathar, Jul 05 2013
No more terms below 10^12. - Hiroaki Yamanouchi, Sep 23 2014.
No additional terms < 10^15. - Chai Wah Wu, Nov 15 2015
No other terms below 10^50. The sequence is likely finite and complete. - Max Alekseyev, Jun 13 2025

Examples

			19 is in the sequence because 19^2=361 and 3+6+1=10.
71 is in the sequence because 71^2=5041 and 5+0+4+1=10.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(5*10^6) | &+Intseq(p^2) eq 10];
  • Maple
    select(p -> isprime(p) and convert(convert(p^2,base,10),`+`)=10, [seq(2*k+1,k=1..100000)]); # Robert Israel, Sep 23 2014
  • Mathematica
    Select[Prime[Range[70000]], Total[IntegerDigits[#^2]]== 10&]

A262713 Numbers k such that the sum of digits of k^2 is 10.

Original entry on oeis.org

8, 19, 35, 46, 55, 71, 80, 145, 152, 179, 190, 251, 332, 350, 361, 449, 451, 460, 548, 550, 649, 710, 800, 1450, 1520, 1790, 1900, 2510, 3320, 3500, 3610, 4490, 4499, 4510, 4600, 5480, 5500, 6490, 7100, 8000, 14500, 15200, 17900, 19000, 20249, 20251, 24499
Offset: 1

Views

Author

Vincenzo Librandi, Sep 28 2015

Keywords

Comments

From Altug Alkan, Sep 29 2015: (Start)
Subsequence of A001651.
If a(n)+1 mod 9 != 0 then a(n)-1 mod 9 = 0;
if a(n)-1 mod 9 != 0 then a(n)+1 mod 9 = 0;
a(n)^2 - 1 mod 9 = 0. (End)
A135027(n)*10^k is a term for all n > 0, k >= 0. - Michael S. Branicky, Aug 19 2021

Examples

			19 is in sequence because 19^2 = 361 and 3+6+1 = 10.
		

Crossrefs

Cf. similar sequences listed in A262711.

Programs

  • Magma
    [n: n in [1..3*10^4] | &+Intseq(n^2) eq 10 ];
    
  • Mathematica
    Select[Range[10^5], Total[IntegerDigits[#^2]] == 10 &]
  • PARI
    for(n=1, 1e6, if (sumdigits(n^2) == 10, print1(n", "))) \\ Altug Alkan, Sep 28 2015
    
  • Python
    # See linked program to go to larger numbers
    def ok(n): return sum(map(int, str(n*n))) == 10
    print(list(filter(ok, range(25000)))) # Michael S. Branicky, Aug 19 2021
Showing 1-2 of 2 results.