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 1-5 of 5 results.

A175518 Numbers n such that 9n+4 are terms in A072841.

Original entry on oeis.org

1, 17, 101, 501, 1627, 2133, 2143, 2201, 2243, 3086, 3536, 3869, 4163, 4398, 4477, 5598, 5948, 5982, 6101, 6998, 7113, 7807, 8501, 8693, 9177, 9928, 10927, 11127, 11177, 11545, 11836, 12427, 12780, 13043, 13998, 14227, 14448, 14517, 14822
Offset: 1

Views

Author

Zak Seidov, Jun 04 2010

Keywords

Comments

(A072841-4)/9.

Crossrefs

A260477 Numbers n where n^2 is an anagram of (n+1)^2 in base 2.

Original entry on oeis.org

9, 17, 33, 49, 50, 65, 73, 77, 85, 86, 97, 106, 129, 137, 149, 157, 161, 165, 178, 186, 193, 201, 212, 213, 225, 226, 257, 265, 273, 279, 281, 285, 300, 305, 307, 310, 317, 321, 325, 332, 334, 345, 355, 365, 366, 378, 385, 393, 394, 413, 426, 427, 449, 469
Offset: 1

Views

Author

Dhilan Lahoti, Aug 28 2015

Keywords

Comments

Base 2 equivalent of A072841.
It appears that one of these numbers has a 1/n chance of being divisible by an odd number n, but a smaller than 1/n chance if n is even.

Examples

			17 is a term of the sequence because its square base 2 (100100001) and 18's square base 2 (101000100) are anagrams.
		

Programs

  • Mathematica
    For[i = 1, i <= 10000, i++,
    If[Sort[IntegerDigits[i^2, 2]] == Sort[IntegerDigits[(i + 1)^2, 2]],
      Print[i]]]
  • PARI
    is(n)=hammingweight(n^2)==hammingweight((n+1)^2) && #binary(n^2)==#binary((n+1)^2) \\ Charles R Greathouse IV, Aug 29 2015

Extensions

a(27)-a(54) from Charles R Greathouse IV, Aug 29 2015

A261749 Numbers k where k^2 is an anagram of (k+2)^2.

Original entry on oeis.org

206, 224, 314, 1799, 2006, 11087, 13364, 15839, 17153, 17324, 20006, 22184, 22706, 24524, 24542, 40031, 40247, 45314, 47069, 48824, 55556, 61694, 64691, 70559, 71351, 89774, 90224, 102374, 108251, 112292, 129824, 132506, 137987, 151757, 154295, 157706, 162089, 167273, 170324, 171557, 175031
Offset: 1

Views

Author

Dhilan Lahoti, Aug 30 2015

Keywords

Comments

Numbers of the form 2*10^k + 6 where k > 1 always appear in this sequence.
Numbers of the form 4*10^k + 31 and 86*10^k + 39 always appear when k > 3.
Similar to A072841 but with (n+2)^2 instead of (n+1)^2.
All numbers in the sequence are of the form 3n + 2.
Multiples of 5 seem to be uncommon.
Another subsequence is numbers of the form 5*(10^(5+9*k)-1)/9 + 1, i.e. 4+9*k 5's followed by a 6: 55556, 55555555555556, 55555555555555555555556, etc. - Robert Israel, Aug 31 2015

Examples

			206 is a term in the sequence because 206^2 (42436) and 208^2 (43264) are anagrams.
		

Crossrefs

Cf. A072841.

Programs

  • Maple
    filter:= proc(n) local L1, L2;
      L1:= convert(n^2,base,10);
      L2:= convert((n+2)^2,base,10);
      evalb(sort(L1)=sort(L2));
    end proc:
    select(filter, [3*i+2 $ i = 1..10^5]); # Robert Israel, Aug 31 2015
  • Mathematica
    Select[Range[10^4], Sort[IntegerDigits[#^2]] == Sort[IntegerDigits[(# + 2)^2]] &] (* Typo fixed by Ivan N. Ianakiev, Sep 02 2015 *)
  • PARI
    isok(n) = vecsort(digits(n^2)) == vecsort(digits((n+2)^2)); \\ Michel Marcus, Aug 31 2015
    
  • Python
    A261749_list = [n for n in range(1,10**6) if sorted(str(n**2)) == sorted(str((n+2)**2))] # Chai Wah Wu, Sep 02 2015

A130868 Numbers k such that the set of digits of k^2 is the same as the set of digits of (k+1)^2.

Original entry on oeis.org

13, 157, 436, 515, 847, 863, 900, 913, 987, 992, 1010, 1100, 1213, 1350, 1358, 1686, 1784, 2015, 2183, 2263, 2313, 2342, 2597, 2778, 3186, 3279, 3347, 3486, 3536, 3592, 3649, 3779, 3899, 3909, 3913, 3971, 3986, 4012, 4099, 4248, 4284, 4286, 4291, 4412
Offset: 1

Views

Author

Tanya Khovanova, Jul 23 2007

Keywords

Examples

			436^2 = 190096 and 437^2 = 190969 consist of the same digits (although not with the same multiplicities).
		

Crossrefs

The sequence A072841 (digits of k^2 are exactly the same (albeit in different order) as the digits of (k+1)^2) is a subsequence of this sequence.

Programs

  • Mathematica
    Select[Range[10000], Union[IntegerDigits[ #^2]] == Union[IntegerDigits[(# + 1)^2]] &]
  • PARI
    isok(n) = Set(digits(n^2)) == Set(digits((n+1)^2)); \\ Michel Marcus, Oct 06 2018

A175519 Prime numbers p such that p^2 and (p+1)^2 are anagrams.

Original entry on oeis.org

13, 157, 4513, 19813, 78241, 98347, 111847, 128047, 130657, 161563, 163363, 168457, 205267, 384817, 599341, 602401, 743179, 765031, 833197, 833467, 964021, 996763, 1023133, 1028047, 1200307, 1235263, 1258267, 1478857, 1523551, 1549957
Offset: 1

Views

Author

Zak Seidov, Jun 04 2010

Keywords

Comments

Prime numbers in A072841.

Examples

			13^2=169 and 14^2=196,
157^2=24649 and 158^2=24964.
		

Crossrefs

Cf. A072841.
Showing 1-5 of 5 results.