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.

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A279426 Numbers k such that k^2 has an odd number of digits and the middle digit is 6.

Original entry on oeis.org

13, 19, 31, 103, 108, 117, 121, 125, 129, 133, 140, 147, 157, 160, 175, 178, 194, 199, 204, 209, 216, 225, 236, 238, 240, 260, 262, 264, 275, 284, 291, 296, 301, 306, 1003, 1008, 1013, 1018, 1023, 1028, 1047, 1052, 1066, 1080, 1094, 1103, 1112, 1121, 1130
Offset: 1

Views

Author

Lars Blomberg, Dec 22 2016

Keywords

Examples

			13^2 = 1(6)9, 133^2 = 17(6)89, 284^2 = 80(6)56.

Links

Crossrefs

Cf. A279420-A279425, A279427-A279429.

Programs

  • Mathematica
    Select[Range[1200],OddQ[IntegerLength[#^2]]&&IntegerDigits[#^2][[(IntegerLength[ #^2]+1)/2]] == 6&] (* Harvey P. Dale, May 28 2023 *)

A279427 Numbers k such that k^2 has an odd number of digits and the middle digit is 7.

Original entry on oeis.org

24, 26, 113, 137, 144, 154, 181, 189, 214, 223, 234, 266, 277, 286, 311, 1033, 1038, 1043, 1057, 1062, 1071, 1076, 1085, 1099, 1108, 1117, 1126, 1139, 1148, 1152, 1161, 1165, 1178, 1182, 1199, 1203, 1228, 1232, 1236, 1240, 1244, 1248, 1252, 1256, 1260, 1264
Offset: 1

Views

Author

Lars Blomberg, Dec 22 2016

Keywords

Examples

			24^2 = 5(7)6, 223^2 = 49(7)29, 1152^2 = 132(7)104.

Links

Crossrefs

Cf. A279420-A279426, A279428-A279429.

Programs

  • Mathematica
    Select[Range[1264], OddQ[len=Length[IntegerDigits[#^2]]]&&Part[IntegerDigits[#^2], (len+1)/2]==7 &] (* Stefano Spezia, Oct 03 2023 *)

A279428 Numbers k such that k^2 has an odd number of digits and the middle digit is 8.

Original entry on oeis.org

17, 22, 28, 104, 109, 122, 126, 141, 151, 164, 167, 184, 192, 197, 202, 207, 221, 232, 268, 279, 293, 298, 303, 308, 316, 1004, 1009, 1014, 1019, 1024, 1029, 1048, 1053, 1067, 1081, 1090, 1104, 1113, 1122, 1135, 1144, 1157, 1170, 1174, 1187, 1191, 1195, 1212
Offset: 1

Views

Author

Lars Blomberg, Dec 22 2016

Keywords

Examples

			17^2 = 2(8)9, 164^2 = 26(8)96, 1024^2 = 104(8)576.

Links

Crossrefs

Cf. A279420-A279427, A279429.

Programs

  • Mathematica
    ond8Q[n_]:=Module[{n2=IntegerDigits[n^2],len},len=Length[n2];OddQ[len]&&n2[[(len+1)/2]] == 8]; Select[Range[1500],ond8Q] (* Harvey P. Dale, Sep 25 2023 *)

A280641 Numbers k such that k^3 has an odd number of digits and the middle digit is 1.

Original entry on oeis.org

1, 6, 8, 23, 44, 45, 102, 106, 110, 114, 117, 121, 137, 148, 152, 153, 162, 168, 176, 185, 189, 194, 206, 210, 478, 488, 512, 533, 553, 560, 574, 580, 626, 639, 655, 662, 669, 671, 676, 682, 683, 684, 685, 693, 704, 710, 730, 731, 737, 742, 758, 761, 767, 771
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 1, 216, 512, 12167, 85184, 91125, 1061208, 1191016, ...

Examples

			1^3 = (1), 114^3 = 148(1)544, 560^3 = 1756(1)6000

Links

Crossrefs

Cf. A280640, A280642-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    a[n_]:=Part[IntegerDigits[n], (Length[IntegerDigits[n]] + 1)/2];
Select[Range[0, 771], OddQ[Length[IntegerDigits[#^3]]] && a[#^3]==1 &] (* Indranil Ghosh, Mar 06 2017 *)
  • PARI
    isok(k) = my(d=digits(k^3)); (#d%2 == 1) && (d[#d\2 +1] == 1);
for(k=0, 771, if(isok(k)==1, print1(k, ", "))); \\ Indranil Ghosh, Mar 06 2017
  • Python
    i=0
j=1
while i<=771:
    n=str(i**3)
    l=len(n)
    if l%2 and n[(l-1)//2]=="1":
        print(str(i), end=', ')
        j+=1
    i+=1 # Indranil Ghosh, Mar 06 2017

A280642 Numbers k such that k^3 has an odd number of digits and the middle digit is 2.

Original entry on oeis.org

5, 9, 103, 113, 133, 146, 151, 154, 165, 180, 198, 202, 470, 473, 493, 496, 504, 507, 521, 531, 538, 542, 566, 569, 581, 591, 593, 599, 612, 618, 620, 650, 654, 673, 681, 686, 703, 711, 715, 728, 729, 732, 740, 779, 801, 829, 841, 850, 855, 856, 857, 858, 874
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 125, 729, 1092727, 1442897, 2352637, 3112136, 3442951, 3652264, ...

Examples

			5^3 = 1(2)5, 180^3 = 583(2)000, 618^3 = 2360(2)9032.

Links

Crossrefs

Cf. A280640-A280641, A280643-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    a[n_]:=Part[IntegerDigits[n],(Length[IntegerDigits[n]]+1)/2];
Select[Range[0,874],OddQ[Length[IntegerDigits[#^3]]] && a[#^3]==2 &] (* Indranil Ghosh, Mar 06 2017 *)
  • PARI
    isok(k) = my(d=digits(k^3)); (#d%2 == 1) && (d[#d\2 +1] == 2);
for(k=0, 874, if(isok(k)==1, print1(k, ", "))); \\ Indranil Ghosh, Mar 06 2017
  • Python
    i=0
j=1
while i<=874:
    n=str(i**3)
    l=len(n)
    if l%2 and n[(l-1)//2]=="2":
        print(str(i), end=', ')
        j+=1
    i+=1 # Indranil Ghosh, Mar 06 2017

A280643 Numbers k such that k^3 has an odd number of digits and the middle digit is 3.

Original entry on oeis.org

29, 34, 39, 46, 118, 125, 141, 142, 155, 161, 170, 211, 213, 477, 489, 511, 522, 526, 529, 535, 554, 573, 582, 586, 589, 631, 632, 633, 645, 663, 680, 691, 699, 723, 733, 744, 747, 770, 785, 790, 816, 817, 832, 854, 859, 863, 869, 873, 878, 892, 897, 901, 923
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 24389, 39304, 59319, 97336, 1643032, 1953125, 2803221, 2863288, ...

Examples

			29^3 = 24(3)89, 161^3 = 417(3)281, 663^3 = 2914(3)4247.

Links

Crossrefs

Cf. A280640-A280642, A280644-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    Select[Range[925],OddQ[len=Length[IntegerDigits[#^3]]]&&Part[IntegerDigits[#^3],(len+1)/2]==3 &] (* Stefano Spezia, Oct 03 2023 *)

A280644 Numbers k such that k^3 has an odd number of digits and the middle digit is 4.

Original entry on oeis.org

7, 104, 112, 140, 143, 158, 166, 186, 188, 195, 465, 467, 490, 541, 558, 572, 595, 598, 604, 605, 606, 607, 613, 616, 622, 625, 630, 634, 635, 640, 643, 647, 653, 667, 675, 679, 687, 702, 712, 718, 720, 727, 734, 738, 759, 764, 783, 787, 802, 810, 815, 818
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 343, 1124864, 1404928, 2744000, 2924207, 3944312, 4574296, 6434856, ...

Examples

			7^3 = 3(4)3, 195^3 = 741(4)875, 640^3 = 2621(4)4000

Links

Crossrefs

Cf. A280640-A280643, A280645-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    Select[Range[1000],OddQ[IntegerLength[#^3]]&&NumberDigit[#^3,(IntegerLength[ #^3]-1)/2]==4&] (* Harvey P. Dale, Aug 12 2021 *)

A280645 Numbers k such that k^3 has an odd number of digits and the middle digit is 5.

Original entry on oeis.org

26, 43, 107, 109, 119, 122, 136, 139, 144, 150, 177, 179, 197, 203, 205, 472, 476, 494, 499, 501, 506, 510, 523, 537, 555, 561, 563, 568, 583, 603, 608, 629, 636, 649, 664, 694, 696, 726, 752, 753, 762, 766, 769, 780, 795, 796, 807, 814, 819, 826, 831, 845
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 17576, 79507, 1225043, 1295029, 1685159, 1815848, 2515456, 2685619, ...

Examples

			26^3 = 17(5)76, 150^3 = 337(5)000, 603^3 = 2192(5)6227

Links

Crossrefs

Cf. A280640-A280644, A280646-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    Select[Range[900],OddQ[IntegerLength[#^3]]&&IntegerDigits[#^3][[(IntegerLength[ #^3]+1)/2]]==5&] (* Harvey P. Dale, Aug 24 2017 *)

A280646 Numbers k such that k^3 has an odd number of digits and the middle digit is 6.

Original entry on oeis.org

22, 25, 27, 36, 37, 124, 129, 134, 147, 156, 160, 169, 469, 497, 503, 527, 532, 540, 547, 548, 549, 565, 571, 587, 602, 609, 652, 670, 672, 678, 688, 698, 713, 716, 722, 735, 741, 746, 751, 754, 755, 789, 794, 797, 798, 805, 813, 820, 828, 849, 866, 883, 887
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 10648, 15625, 19683, 46656, 50653, 1906624, 2146689, 2406104, ...

Examples

			22^3 = 10(6)48, 156^3 = 379(6)416, 678^3 = 3116(6)5752.

Links

Crossrefs

Cf. A280640-A280645, A280647-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    Select[Range[887], OddQ[len=Length[IntegerDigits[#^3]]]&&Part[IntegerDigits[#^3], (len+1)/2]==6 &] (* Stefano Spezia, Oct 03 2023 *)

A280647 Numbers k such that k^3 has an odd number of digits and the middle digit is 7.

Original entry on oeis.org

31, 32, 105, 111, 128, 130, 149, 167, 173, 191, 192, 475, 483, 484, 491, 509, 524, 530, 534, 545, 546, 550, 556, 559, 584, 590, 592, 597, 614, 619, 624, 628, 637, 641, 665, 668, 692, 701, 725, 743, 750, 760, 781, 793, 809, 824, 836, 837, 843, 852, 861, 864
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 29791, 32768, 1157625, 1367631, 2097152, 2197000, 3307949, 4657463, ...

Examples

			31^3 = 29(7)91, 191^3 = 696(7)871, 619^3 = 2371(7)6659.

Links

Crossrefs

Cf. A280640-A280646, A280648-A280649, A181354.
See A279420-A279429 for a k^2 version.
See A279430-A279431 for a k^2 version in base 2.

Programs

  • Mathematica
    Select[Range[865], OddQ[len=Length[IntegerDigits[#^3]]]&&Part[IntegerDigits[#^3], (len+1)/2]==7 &] (* Stefano Spezia, Oct 03 2023 *)
Previous Showing 11-20 of 23 results. Next

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