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.

A257123 Numbers n such that the decimal expansions of both n and n^2 have 2 as smallest digit and 7 as largest digit.

Original entry on oeis.org

275, 2574, 2725, 2765, 4762, 5725, 6762, 7244, 7262, 23765, 25744, 27244, 27325, 27434, 27465, 27525, 27632, 27665, 47725, 52275, 52376, 52475, 52576, 52675, 57242, 67426, 72266, 72275, 72424, 72426, 72576, 72624, 73325, 73725, 74326, 75725, 233725, 233744
Offset: 1

Views

Author

Felix Fröhlich, Apr 25 2015

Keywords

Links

Crossrefs

Cf. A137094, A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257368, A257485, A257486, A257498, A257534.

Programs

  • PARI
    is(n) = vecmin(digits(n))==2 && vecmin(digits(n^2))==2 && vecmax(digits(n))==7 && vecmax(digits(n^2))==7

A257498 Numbers n such that the decimal expansions of both n and n^2 have 3 as the digit with the smallest value and 8 as the digit with the largest value.

Original entry on oeis.org

7378, 66834, 67438, 67738, 73874, 86356, 577378, 577438, 586374, 658388, 666834, 667438, 676438, 683874, 683876, 684438, 688374, 738474, 738538, 743878, 744538, 744738, 747378, 747438, 763844, 764438, 765738, 766384, 863388, 863474, 873874, 874378, 875434
Offset: 1

Views

Author

Felix Fröhlich, Apr 27 2015

Keywords

Links

Crossrefs

Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257123, A257368, A257485, A257486, A238553, A257534.

Programs

  • Mathematica
    fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 2}] == 0, Plus @@ Take[c, {9, 10}] == 0, c[[3]] > 0, c[[8]] > 0]]; Select[Range@ 1000000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, May 05 2015 *)
  • PARI
    is(n) = vecmin(digits(n))==3 && vecmin(digits(n^2))==3 && vecmax(digits(n))==8 && vecmax(digits(n^2))==8

A238553 Numbers n such that the decimal expansions of both n and n^2 have 3 as the digit with the smallest value and 9 as the digit with the largest value.

Original entry on oeis.org

5793, 5963, 6593, 6963, 7593, 8593, 9357, 9463, 9663, 9883, 9934, 9937, 9938, 57937, 58893, 58937, 58963, 59463, 59537, 59543, 59663, 59736, 59833, 59863, 59883, 65937, 66893, 68963, 69537, 69634, 69883, 73956, 73957, 79583, 79836, 79837, 79934, 83594, 85938
Offset: 1

Views

Author

Felix Fröhlich, Apr 27 2015

Keywords

Examples

			5793 is in the sequence because its smallest digit is 3 and its largest digit is 9, and this is also true of 5793^2 = 33558849.
5833 is not in the sequence because 5833^2 = 34023889, which contains a 0 and a 2.

Links

Crossrefs

Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257123, A257368, A257485, A257486, A257498, A257534, A254071, A254072, A254074.

Programs

  • Mathematica
    fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 2}] == 0, Last@ c == 0, c[[3]] > 0, c[[9]] > 0]]; Select[Range@ 90000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, May 05 2015 *)
  • PARI
    is(n) = vecmin(digits(n))==3 && vecmin(digits(n^2))==3 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9

A254072 Numbers n such that the decimal expansions of both n and n^2 have 4 as the digit with the smallest value and 9 as the digit with the largest value.

Original entry on oeis.org

974, 9476, 9874, 69684, 94588, 94657, 94788, 94867, 97457, 99476, 99784, 669684, 677974, 697764, 699684, 699764, 699784, 746957, 869457, 945857, 946878, 946888, 947457, 947574, 947886, 947887, 947976, 948678, 974457, 974474, 984878, 998784, 6669684, 6696684
Offset: 1

Views

Author

Felix Fröhlich, May 03 2015

Keywords

Links

Crossrefs

Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257123, A257368, A257485, A257486, A257498, A238553, A257534, A254071.

Programs

  • Mathematica
    fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 3}] == 0, Last@ c == 0, c[[4]] > 0, c[[9]] > 0]]; Select[Range@ 1000000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, May 05 2015 *)
  • PARI
    is(n) = vecmin(digits(n))==4 && vecmin(digits(n^2))==4 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9

A254074 Numbers k such that the decimal expansions of both k and k^2 have 5 as the digit with the smallest value and 9 as the digit with the largest value.

Original entry on oeis.org

759576, 97759786, 97957576, 887579686, 987759576, 987859786, 7599859786, 7679576587, 8756697886, 8766958976, 9775989867, 9897756766, 9978965766, 76797588887, 88766997576, 97978858887, 99777685676, 99789658666, 99879856766, 767897685676, 869866586666
Offset: 1

Views

Author

Felix Fröhlich, May 03 2015

Keywords

Comments

The first digit of a term is either 7, 8 or 9 and the last digit is either 5, 6 or 7. Conjecture: no term is a multiple of 5. - Chai Wah Wu, Sep 10 2017

Links

Crossrefs

Cf. A137147, A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257123, A257368, A257485, A257486, A257498, A238553, A257534, A254071.

Programs

  • Mathematica
    fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 4}] == 0, Last@ c == 0, c[[5]] > 0, c[[9]] > 0]]; Select[Range@ 10000000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, May 05 2015 *)
  • PARI
    is(n) = vecmin(digits(n))==5 && vecmin(digits(n^2))==5 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9

Extensions

a(14)-a(21) from Hiroaki Yamanouchi, May 07 2015
Showing 1-5 of 5 results.

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