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 1-3 of 3 results.

A159463 Numbers n with property that sod(n^3) = 6^3.

Original entry on oeis.org

3848163483, 4462569999, 4479677412, 4586158119, 4594661259, 4594665192, 4594700889, 4625720379, 4641588459, 5644008999, 5828410842, 5833034823, 5838252576, 5848025709, 6453471192, 6617331999, 6619097067, 6686657169, 7107126942, 7230291999, 7277907183
Offset: 1

Views

Author

Zak Seidov, Apr 12 2009

Keywords

Comments

Numbers n with property that A007953(n^3) = 6^3.

Examples

			3848163483^3 = 56984998629886989599887999587, 5+6+9+8+4+9+9+8+6+2+9+8+8+6+9+8+9+5+9+9+8+8+7+9+9+9+5+8+7 = 216 = 6^3.
		

Crossrefs

Cf. A054966 Numbers that are congruent to {0, 1, 8} mod 9. A054966 Possible sums of digits of cubes. A067075 a(n) = smallest number m such that the sum of the digits of m^3 is equal to n^3. A007953 Digital sum (i.e., sum of digits) of n.
Numbers n such that sum of digits of n^3 is k^3: A107679 (k=2), A290842 (k=3), A290843 (k=4), A159462 (k=5), this sequence (k=6).

Extensions

a(16)-a(21) from Seiichi Manyama, Aug 12 2017

A290842 Numbers k such that the sum of digits of k^3 is 3^3 = 27.

Original entry on oeis.org

27, 33, 36, 39, 42, 54, 57, 69, 72, 75, 78, 84, 87, 93, 105, 108, 111, 114, 135, 138, 147, 162, 165, 168, 174, 177, 219, 222, 225, 228, 231, 234, 258, 267, 270, 273, 276, 285, 291, 294, 312, 318, 321, 330, 342, 345, 348, 351, 360, 369, 381, 384, 390, 405, 417
Offset: 1

Views

Author

Seiichi Manyama, Aug 12 2017

Keywords

Comments

It is obvious that if k is in this sequence, then so is 10*k. Additionally, this sequence contains other infinite subsequences. For example, 10^(2*k) + 10^k + 1 is in this sequence for all k > 0. - Altug Alkan, Aug 12 2017

Examples

			27^3 = 19683, 1 + 9 + 6 + 8 + 3 = 27 = 3^3.
		

Crossrefs

Numbers k such that sum of digits of k^3 is m^3: A107679 (m=2), this sequence (m=3), A290843 (m=4), A159462 (m=5), A159463 (m=6).
Cf. A067075.

Programs

  • PARI
    isok(n) = sumdigits(n^3) == 27; \\ Altug Alkan, Aug 12 2017

A290944 Primes p such that sum of digits of p^3 is a perfect square.

Original entry on oeis.org

3, 1753, 1999, 2389, 2713, 3301, 3361, 3529, 3583, 3607, 3631, 3643, 3697, 3889, 3907, 4093, 4099, 4129, 4153, 4159, 4243, 4423, 4591, 4639, 4813, 5167, 5449, 5503, 5527, 5563, 5683, 5689, 5827, 6199, 6211, 6427, 6529, 6553, 6691, 6709, 6883, 6949, 6961, 6997
Offset: 1

Views

Author

K. D. Bajpai, Aug 14 2017

Keywords

Comments

All the terms in this sequence, except a(1), are congruent to 1 mod 3.
After a(1), all the terms are congruent to {1, 4, 7} mod 9.

Examples

			a(1) = 3 is prime: 3^3 = 27; 2 + 7 = 9 = 3^2.
a(2) = 1753 is prime: 1753^3 = 5386984777; 5 + 3 + 8 + 6 + 9 + 8 + 4 + 7 + 7 + 7 = 64 = 8^2.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(1000) | IsSquare(&+Intseq(p^3))];
    
  • Maple
    f:= n->add(d, d=convert(n^3, base, 10)):
    select(t -> type(sqrt(f(t)), integer), [seq(ithprime(m), m=1..10^3)]);
  • Mathematica
    Select[Prime[Range[2000]], IntegerQ[Sqrt[Plus @@ IntegerDigits[#^3]]] &]
  • PARI
    forprime(p=1, 5000, if(issquare(sumdigits(p^3)), print1(p, ", ")));
    
  • PARI
    is(n) = ispseudoprime(n) && issquare(sumdigits(n^3)) \\ Felix Fröhlich, Aug 14 2017
Showing 1-3 of 3 results.