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 1-10 of 11 results. Next

A280649 Numbers k such that k^3 has an odd number of digits and the middle digit is 9.

Original entry on oeis.org

28, 33, 41, 108, 132, 157, 159, 175, 178, 181, 184, 187, 190, 193, 196, 204, 207, 209, 466, 474, 480, 486, 492, 508, 514, 515, 518, 519, 528, 536, 539, 552, 570, 588, 611, 627, 638, 648, 651, 657, 658, 659, 660, 706, 707, 708, 714, 719, 745, 757, 763, 765, 772
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 21952, 35937, 68921, 1259712, 2299968, 3869893, 4019679, 5359375, ...

Examples

			28^3 = 21(9)52, 181^3 = 592(9)741, 536^3 = 1539(9)0656.

Links

Crossrefs

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

Programs

  • Mathematica
    ond9Q[n_]:=Module[{idn=IntegerDigits[n^3],len},len=Length[idn];OddQ[len]&&idn[[(len+1)/2]]==9]; Select[Range[800],ond9Q] (* Harvey P. Dale, Mar 14 2018 *)

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 *)

A280648 Numbers k such that k^3 has an odd number of digits and the middle digit is 8.

Original entry on oeis.org

2, 24, 35, 38, 120, 127, 131, 138, 145, 172, 174, 182, 183, 208, 212, 215, 471, 481, 482, 485, 495, 505, 516, 517, 544, 551, 567, 594, 601, 610, 617, 621, 644, 646, 674, 677, 689, 736, 739, 749, 756, 768, 773, 774, 775, 776, 786, 799, 803, 812, 821, 830, 835
Offset: 1

Views

Author

Lars Blomberg, Jan 07 2017

Keywords

Comments

The sequence of cubes starts: 8, 13824, 42875, 54872, 1728000, 2048383, 2248091, 2628072, ...

Examples

			2^3 = (8), 172^3 = 508(8)448, 610^3 = 2269(8)1000.

Links

Crossrefs

Cf. A280640-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[835], OddQ[len=Length[IntegerDigits[#^3]]]&&Part[IntegerDigits[#^3], (len+1)/2]==8 &] (* Stefano Spezia, Oct 03 2023 *)

A280650 Numbers k such that k^3 has an odd number of digits in base 2 and the middle digit is 0.

Original entry on oeis.org

0, 3, 4, 12, 16, 17, 29, 30, 31, 43, 44, 46, 48, 50, 64, 65, 68, 78, 79, 80, 102, 104, 105, 107, 108, 109, 112, 114, 116, 117, 118, 121, 127, 163, 167, 169, 170, 172, 173, 174, 175, 176, 179, 183, 186, 187, 188, 189, 191, 192, 193, 195, 196, 198, 200, 202, 203
Offset: 1

Views

Author

Lars Blomberg, Jan 12 2017

Keywords

Examples

			3^3 = 11(0)11_2, 43^3 = 10011011(0)10010011_2, 117^3 = 1100001110(0)0001001101_2.

Links

Crossrefs

Cf. A280651.
See A279430-A279431 for a k^2 version.
See A280640-A280649 for a base-10 version.
See A279420-A279429 for a k^2, base-10 version.

Programs

  • Mathematica
    a[n_]:=Part[IntegerDigits[n, 2], (Length[IntegerDigits[n,2]] + 1)/2];
Select[Range[0, 203], OddQ[Length[IntegerDigits[#^3, 2]]] && a[#^3]==0 &] (* Indranil Ghosh, Mar 06 2017 *)
md0Q[n_]:=Module[{idn2=IntegerDigits[n^3,2],len},len=Length[idn2];OddQ[ len] &&idn2[[(len+1)/2]]==0]; Select[Range[0,250],md0Q] (* Harvey P. Dale, Dec 15 2019 *)
  • PARI
    isok(k) = my(d=digits(k^3, 2)); (#d%2 == 1) && (d[#d\2 +1] == 0);
for(k=0, 203, if(k==0 || isok(k)==1, print1(k,", "))); \\ Indranil Ghosh, Mar 06 2017
  • Python
    i=0
j=1
while i<=203:
    n=str(bin(i**3)[2:])
    l=len(n)
    if l%2==1 and n[(l-1)/2]=="0":
        print (str(i))+",",
        j+=1
    i+=1 # Indranil Ghosh, Mar 06 2017
Showing 1-10 of 11 results. Next

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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