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.

Previous Showing 11-18 of 18 results.

A228542 Numbers that are sums of two coprime positive fifth powers.

Original entry on oeis.org

2, 33, 244, 275, 1025, 1267, 3126, 3157, 3368, 4149, 7777, 10901, 16808, 16839, 17050, 17831, 19932, 24583, 32769, 33011, 35893, 49575, 59050, 59081, 60073, 62174, 75856, 91817, 100001, 100243, 116807, 159049, 161052, 161083, 161294, 162075, 164176, 168827
Offset: 1

Views

Author

Arkadiusz Wesolowski, Aug 25 2013

Keywords

Examples

			244 is in the sequence since 1^5 + 3^5 = 244 and (1, 3) = 1.
		

Crossrefs

Supersequence of A228556. Cf. A002561, A055014.

Programs

  • Magma
    lst:=[]; for m in [2..168827] do f:=func; if f(m)[1] gt 0 and GCD(f(m)[1], f(m)[2]) eq 1 then Append(~lst, m); end if; end for; lst; // Arkadiusz Wesolowski, Dec 19 2020

A362945 Numbers k such that k + the sum of the fifth powers of its digits is again a fifth power.

Original entry on oeis.org

0, 210, 66374, 76933, 294137, 722571, 741300, 1023716, 2412593, 3959235, 4022940, 5090402, 6351886, 7821198, 9653864, 11808061, 11814811, 20427955, 24190287, 24239133, 24245187, 33518020, 33532714, 33536551, 39060306, 52476271, 52480534, 69255266, 69265142, 79091461, 89980491, 90147222
Offset: 0

Views

Author

M. F. Hasler, Jun 15 2023

Keywords

Crossrefs

Cf. A000584 (4th powers), A055014 (sum of 5th powers of decimal digits).
Cf. A362953 (same for 3rd powers), A362954 (same for 4th powers).

Programs

  • PARI
    is_A362945(n,p=5)=ispower(vecsum([d^p|d<-digits(n)])+n,p)
    for(n=0,1e8, is_A362945(n) && print1(n", "))
    
  • Python
    ispower5 = lambda n: n==round(n**.2)**5
    is_A362945 = lambda n: ispower5(sum(int(d)**5 for d in str(n))+n)
    def A362945(n, A=[0]):
        while len(A) < n:
            A.append(A[-1]+1)
            while not is_A362945(A[-1]): A[-1]+=1
        return A[n]

A031193 Numbers having period-22 5-digitized sequences.

Original entry on oeis.org

3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99, 102, 105, 108, 111, 114, 117, 120, 123, 126, 129, 132, 135, 138, 141, 144, 147, 150, 153, 156, 159, 162, 165, 168, 171, 174
Offset: 1

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Author

Keywords

Comments

This sequence consists of those n whose trajectory under the "sum of fifth power of digits" function has period 22. All elements are multiples of 3, but some multiples of 3, the least being 0 and 888, are not in the sequence. - David W. Wilson, Aug 03 2005
Multiples of 3 have period 22 (like 3), period 1 (like 888), or period 2 (like 38889). The absence of 888 from this sequence is enough to demonstrate that it is not a Beatty sequence. - Charles R Greathouse IV, Jan 27 2022

Crossrefs

Cf. A055014 (sum of 5th powers of digits).

A055208 Table read by ascending antidiagonals: T(n,k) (n >= 1, k >= 1) is the sum of k-th powers of digits of n.

Original entry on oeis.org

1, 2, 1, 3, 4, 1, 4, 9, 8, 1, 5, 16, 27, 16, 1, 6, 25, 64, 81, 32, 1, 7, 36, 125, 256, 243, 64, 1, 8, 49, 216, 625, 1024, 729, 128, 1, 9, 64, 343, 1296, 3125, 4096, 2187, 256, 1, 1, 81, 512, 2401, 7776, 15625, 16384, 6561, 512, 1, 2, 1, 729, 4096, 16807, 46656, 78125
Offset: 1

Views

Author

Henry Bottomley, Jun 19 2000

Keywords

Examples

			T(34,2) = 3^2 + 4^2 = 25.
From _Georg Fischer_, Mar 01 2022: (Start)
Array T(n, k) (n >= 1, k >= 1) begins:
  1,   1,   1,   1, ...
  2,   4,   8,  16, ...
  3,   9,  27,  64, ...
  4,  16,  64, 256, ...
  ...
(End)
		

Crossrefs

Extensions

Definition clarified by Georg Fischer, Mar 01 2022

A270540 Numbers that are equal to the number of their digits multiplied by the sum of the fifth powers of the digits.

Original entry on oeis.org

0, 1, 1232, 4100, 268542
Offset: 1

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Author

Keywords

Comments

Terms up to 10^8.
No further terms after 10^7 since 10^k > k^2*9^5 beyond that point. - Ray Chandler, Apr 01 2016

Examples

			4100 is a term because 4100 = 4*(4^5+1^5+0^5+0^5).
		

Crossrefs

Cf. A055014.

Programs

  • Mathematica
    Position[ Table[ IntegerLength[ k] Sum[( Floor[k/10^n] - 10 Floor[k/10^(n + 1)])^5, {n, 0, IntegerLength@ k}] - k, {k, 1, 10^6}], 0] // Flatten = {1, 1232, 4100, 268542}
    Select[Range[10^7],With[{id=IntegerDigits[#]},#==Length[id]*Plus@@(id^5)]&] (* Ray Chandler, Apr 01 2016 *)
  • PARI
    isok(n) = my(d=digits(n)); n == #d*sum(k=1, #d, d[k]^5); \\ Michel Marcus, Mar 25 2016

Extensions

a(5) from Michel Marcus, Mar 25 2016

A341286 Numbers k such that k plus the sum of the fifth powers of the digits of k is a cube.

Original entry on oeis.org

0, 2435, 3403, 5625, 8781, 11140, 22664, 23325, 32908, 33346, 34822, 41332, 58555, 99180, 103925, 109272, 133118, 136386, 145263, 170740, 180105, 182142, 194261, 207459, 208813, 228224, 249945, 251991, 266080, 305840, 341539, 351824, 359720, 372287, 380064, 415434
Offset: 1

Views

Author

Will Gosnell, Feb 08 2021

Keywords

Examples

			2435 is a term since 2435 + 2^5 + 4^5 + 3^5 + 5^5 = 19^3;
3403 is a term since 3403 + 3^5 + 4^5 + 0^5 + 3^5 = 17^3.
		

Crossrefs

Cf. A055014 (sum of 5th powers of digits).

Programs

  • Maple
    filter:= proc(n) local x, d;
      x:= n + add(d^5, d = convert(n, base, 10));
      surd(x, 3)::integer
    end proc:
    select(filter, [$0..10^5]); # Robert Israel, Feb 09 2021
  • Mathematica
    Select[Range[0, 500000], IntegerQ@ Power[# + Total[IntegerDigits[#]^5], 1/3] &] (* Michael De Vlieger, Feb 22 2021 *)
    Select[Range[0,416000],IntegerQ[Surd[#+Total[IntegerDigits[#]^5],3]]&] (* Harvey P. Dale, Jul 19 2022 *)
  • PARI
    isok(k) = ispower(k+vecsum(apply(x->x^5, digits(k))), 3); \\ Michel Marcus, Feb 09 2021
    
  • Python
    from sympy import integer_nthroot
    def powsum(n): return sum(int(d)**5 for d in str(n))
    def ok(n): return integer_nthroot(n + powsum(n), 3)[1]
    def aupto(lim):
      alst = []
      for k in range(lim+1):
        if ok(k): alst.append(k)
      return alst
    print(aupto(415434)) # Michael S. Branicky, Feb 22 2021

Extensions

More terms from Michel Marcus, Feb 09 2021
a(1)=0 prepended by Michael S. Branicky, Feb 22 2021

A355708 Irregular triangle read by rows in which row n lists the possible periods for the iterations of the map sum of n-th powers of digits.

Original entry on oeis.org

1, 1, 8, 1, 2, 3, 1, 2, 7, 1, 2, 4, 6, 10, 12, 22, 28, 1, 2, 3, 4, 10, 30, 1, 2, 3, 6, 12, 14, 21, 27, 30, 56, 92, 1, 25, 154, 1, 2, 3, 4, 8, 10, 19, 24, 28, 30, 80, 93, 1, 6, 7, 17, 81, 123
Offset: 1

Views

Author

Mohammed Yaseen, Jul 14 2022

Keywords

Examples

			Triangle begins:
  1;
  1, 8;
  1, 2, 3;
  1, 2, 7;
  1, 2, 4, 6, 10, 12, 22, 28;
  1, 2, 3, 4, 10, 30;
  1, 2, 3, 6, 12, 14, 21, 27, 30, 56, 92;
  1, 25, 154;
  1, 2, 3, 4, 8, 10, 19, 24, 28, 30, 80, 93;
  1, 6, 7, 17, 81, 123;
  ...
		

Crossrefs

Periods of sum of m-th powers of digits iterated: A031176 (m=2), A031178 (m=3), A031182 (m=4), A031186 (m=5), A031195 (m=6), A031200 (m=7), A031211 (m=8), A031212 (m=9), A031213 (m=10).
Sum of m-th powers of digits: A007953 (m=1), A003132 (m=2), A055012 (m=3), A055013 (m=4), A055014 (m=5), A055015 (m=6), A123253 (m=7), A210840 (m=8).

A359610 Numbers k such that the sum of the 5th powers of the digits of k is prime.

Original entry on oeis.org

11, 101, 110, 111, 119, 128, 133, 182, 188, 191, 218, 223, 227, 229, 232, 247, 272, 274, 281, 292, 313, 322, 331, 337, 346, 359, 364, 368, 373, 377, 379, 386, 395, 397, 427, 436, 463, 472, 478, 487, 539, 557, 568, 575, 577, 586, 593, 634, 638, 643, 658, 667
Offset: 1

Views

Author

José Hernández, Jan 06 2023

Keywords

Comments

It is easy to establish that the sequence is infinite: if x is in the sequence, so is 10*x.
Alternatively: the sequence is infinite as the sequence contains all numbers consisting of a prime number of 1s and an arbitrary number of 0s. - Charles R Greathouse IV, Jan 06 2023

Examples

			11 is a term since 1^5 + 1^5 = 2 is prime.
		

Crossrefs

A031974 is a subsequence.
Cf. A055014 (sum of the 5th powers of digits).

Programs

  • Mathematica
    top = 999; (* Find all terms <= top *)
    For[t = 11, t <= top, t++, k = IntegerLength[t]; sum = 0;
       For[e = 0, e <= k - 1, e++, sum = sum + NumberDigit[t, e]^5];
          If[PrimeQ[sum] == True, Print[t]]]
    Select[Range[670],PrimeQ[Total[IntegerDigits[#]^5]] &] (* Stefano Spezia, Jan 08 2023 *)
  • PARI
    isok(k) = isprime(vecsum(apply(x->x^5, digits(k)))); \\ Michel Marcus, Jan 07 2023
Previous Showing 11-18 of 18 results.