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 1-7 of 7 results.

A162999 Positions of primes in A119509.

Original entry on oeis.org

2, 3, 5, 7, 10, 13, 15, 16, 21, 22, 26, 28, 34, 38, 39, 43, 45, 48, 53, 59, 69, 83, 84, 87, 88, 92, 103, 109, 112, 124, 130, 132, 135, 145, 146, 150, 153, 156, 162, 175, 177, 178, 183, 187, 190, 196, 200, 201, 217, 230, 238, 240, 250, 267, 272, 279, 280, 286, 290, 294
Offset: 1

Views

Author

Zak Seidov, Jul 20 2009

Keywords

Comments

There are exactly 87 primes in A119509. Cf. A162950 primes in A119509 Numbers whose square contains no repeated digit.

Examples

			Rest 27 terms after a(60)=294 are: 309, 316, 318, 320, 321, 330, 337, 355, 362, 367, 368, 378, 385, 394, 395, 397, 401, 408, 411, 413, 418, 429, 430, 435, 451, 477, 481.
		

A162950 Primes whose square contains no repeated digit.

Original entry on oeis.org

2, 3, 5, 7, 13, 17, 19, 23, 29, 31, 37, 43, 53, 59, 61, 71, 73, 79, 89, 113, 137, 179, 181, 191, 193, 199, 233, 269, 281, 311, 353, 367, 397, 463, 487, 509, 557, 571, 593, 647, 661, 677, 709, 733, 757, 797, 829, 839, 929, 1117, 1277, 1307, 1433, 1873, 1949
Offset: 1

Views

Author

Claudio Meller, Jul 18 2009

Keywords

Comments

Or: primes in A119509.
There are only 87 terms, the last being 21397.

Crossrefs

Cf. A119509.

Programs

  • Magma
    [p: p in PrimesUpTo(21397) | #Set(d) eq #d where d is Intseq(p^2)]; // Bruno Berselli, Aug 02 2011
    
  • Mathematica
    t={}; Do[p=Prime[n]; If[Max[DigitCount[p^2]]<= 1,AppendTo[t,p]],{n,300}]; t   (* Jayanta Basu, May 10 2013 *)
  • PARI
    is(n)=if(n<21398 && isprime(n), n=digits(n^2); #v==#vecsort(v,,8), 0) \\ Charles R Greathouse IV, May 10 2013

Extensions

Keyword:base added by R. J. Mathar, Jul 19 2009

A226796 Number of nonnegative numbers x < 10^n such that the digits of x^2 occur with an equal frequency of 1.

Original entry on oeis.org

10, 59, 221, 441, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611, 611
Offset: 1

Views

Author

T. D. Noe, Jun 21 2013

Keywords

Examples

			All numbers 0 to 9 have squares containing only digits of frequency 1: 0, 1, 4, 9, 16, 25, 36, 49, 64, 81. See A119509 for the positive terms.
		

Crossrefs

Cf. A119509 (positive terms x), A225428 (for 2 digits).

Programs

  • Mathematica
    cnt = 0; x = 0; Table[While[x < 10^n, If[Union[Last[Transpose[Tally[IntegerDigits[x^2]]]]] == {1}, cnt++]; x++]; cnt, {n, 5}]

A376897 Positive numbers k such that all the digits in the octal expansion of k^2 are distinct.

Original entry on oeis.org

1, 2, 4, 5, 7, 13, 14, 15, 18, 20, 21, 28, 30, 37, 39, 43, 44, 45, 53, 55, 63, 78, 84, 103, 110, 113, 117, 127, 149, 155, 156, 161, 162, 172, 173, 174, 175, 179, 220, 236, 242, 270, 286, 293, 299, 301, 340, 343, 350, 356, 361, 395, 407, 412, 425, 439, 461, 475, 499, 674, 819, 1001, 1211, 1230, 1244, 1323, 1764, 2450, 2751, 3213
Offset: 1

Views

Author

Kalle Siukola, Oct 08 2024

Keywords

Comments

There are no terms >= 2^12 because 2^24-1 is the largest eight-digit octal number.

Examples

			110 is in the sequence because 110^2 = 12100 = 27504_8 and no octal digit occurs more than once.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[2^12], DuplicateFreeQ[IntegerDigits[#^2, 8]] &] (* Michael De Vlieger, Oct 12 2024 *)
  • Python
    for k in range(1, 2**12):
        octal = format(k**2, "o")
        if len(octal) == len(set(octal)): print(k, end=",")

A225565 Numbers with repeated digits, whose squares do not contain any repeated digits.

Original entry on oeis.org

33, 44, 55, 66, 99, 113, 116, 117, 118, 133, 144, 181, 191, 199, 224, 226, 228, 232, 233, 252, 272, 282, 292, 299, 311, 322, 323, 353, 442, 445, 557, 616, 626, 661, 677, 686, 717, 733, 737, 757, 777, 778, 797, 799, 855, 884, 889, 929, 1017, 1113, 1117
Offset: 1

Views

Author

Jayanta Basu, May 10 2013

Keywords

Comments

Subsequence of A119509. There are a total of 274 such terms. a(274)=99066.

Examples

			117 is a member since it has repeated digits but 117^2=13689 contains no repeated digits.
		

Crossrefs

Cf. A119509.

Programs

  • Mathematica
    mx[n_]:=Max[DigitCount[n]]; Select[Range[1150],mx[#]>1 && mx[#^2]<=1 &]

A259187 Primes p such that both p and p^2 are distinct-digit numbers.

Original entry on oeis.org

2, 3, 5, 7, 13, 17, 19, 23, 29, 31, 37, 43, 53, 59, 61, 71, 73, 79, 89, 137, 179, 193, 269, 281, 367, 397, 463, 487, 509, 571, 593, 647, 709, 829, 839, 1307, 1873, 2069, 2731, 2801, 3041, 4157, 4967, 4987, 6043, 7549, 7621, 8623, 21397
Offset: 1

Views

Author

Zak Seidov, Jun 20 2015

Keywords

Comments

Corresponding squares are 4, 9, 25, 49, 169, 289, 361, 529, 841, 961, 1369, 1849, 2809, 3481, 3721, 5041, 5329, 6241, 7921, 18769, 32041, 37249, 72361, 78961, 134689, 157609, 214369, 237169, 259081, 326041, 351649, 418609, 502681, 687241, 703921, 1708249, 3508129, 4280761, 7458361, 7845601, 9247681, 17280649, 24671089, 24870169, 36517849, 56987401, 58079641, 74356129, 457831609 (subsequence of A078255).

Crossrefs

Subsequence of A029743 and of A119509. Cf. A078255.

Programs

  • Mathematica
    Select[Prime[Range[2500]],Max[DigitCount[#]]<2&&Max[DigitCount[#^2]]<2&] (* Harvey P. Dale, May 25 2020 *)

A376814 a(n) is the number of squares that have all digits distinct in base n.

Original entry on oeis.org

2, 2, 7, 7, 21, 42, 71, 268, 611, 1352, 3099, 8471, 23877, 63564, 182771, 527001, 1671752, 5055853
Offset: 2

Views

Author

Robert Israel, Oct 09 2024

Keywords

Examples

			a(4) = 7 because the only squares with distinct digits in base 4 are 0^2 = 0_4, 1^2 = 1_4, 2^2 = 10_4, 3^2 = 21_4, 6^2 = 210_4, 7^2 = 301_4 and 15^2 = 3201_4.
		

Crossrefs

Programs

  • Maple
    f:= proc(b) local k,t,F;
     t:= 0;
     for k from 0 to floor(sqrt(b^b-1)) do
       F:= convert(k^2, base, b);
       if nops(F) = nops(convert(F,set)) then t:= t+1 fi;
     od;
     t
    end proc:
    map(f, [$2..12]);
  • Python
    from math import isqrt
    from sympy.ntheory import digits
    def A376814(n): return sum(1 for k in range(isqrt(n**n-1)+1) if len(s:=digits(k**2,n)[1:])==len(set(s))) # Chai Wah Wu, Oct 09 2024

Extensions

a(15)-a(16) from Michael S. Branicky, Oct 09 2024
a(17) from Michael S. Branicky, Oct 10 2024
a(18) from Michael S. Branicky, Oct 14 2024
a(19) from Michael S. Branicky, Oct 31 2024
Showing 1-7 of 7 results.