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 1-3 of 3 results.

A381837 k/16 is in this list if A053737(k) < A235127(k), i.e. if digitsum(k, 4) < valuation(k, 4).

Original entry on oeis.org

1, 4, 8, 16, 20, 32, 48, 64, 68, 80, 96, 128, 144, 192, 256, 260, 272, 288, 320, 336, 384, 448, 512, 528, 576, 640, 768, 832, 1024, 1028, 1040, 1056, 1088, 1104, 1152, 1216, 1280, 1296, 1344, 1408, 1536, 1600, 1792, 2048, 2064, 2112, 2176, 2304, 2368, 2560, 2816
Offset: 1

Views

Author

Peter Luschny, Mar 08 2025

Keywords

Crossrefs

Cf. A371176 (base 2), A381838 (base 3), A381836 (base 5).

Programs

  • Maple
    aList := upto -> local k; [seq(k/16, k in select(n -> add(convert(n, base, 4)) < padic[ordp](n, 4), [seq(16..upto,16)]))]: aList(46000);
  • Mathematica
    Select[Range[46000],DigitSum[#,4]Stefano Spezia, Mar 08 2025 *)
  • SageMath
    def aList(upto, b): return [n/b^2 for n in srange(b^2, upto, b^2) if sum(n.digits(b)) < valuation(n, b)]
    print(aList(46000, 4))

A381838 k/9 is in this list if A053735(k) < A007949(k), i.e. if digitsum(k, 3) < valuation(k, 3).

Original entry on oeis.org

1, 3, 6, 9, 12, 18, 27, 30, 36, 45, 54, 63, 81, 84, 90, 99, 108, 117, 135, 162, 171, 189, 216, 243, 246, 252, 261, 270, 279, 297, 324, 333, 351, 378, 405, 432, 486, 495, 513, 540, 567, 594, 648, 729, 732, 738, 747, 756, 765, 783, 810, 819, 837, 864, 891, 918, 972, 981, 999
Offset: 1

Views

Author

Peter Luschny, Mar 08 2025

Keywords

Crossrefs

Cf. A371176 (base 2), A381837 (base 4), A381836 (base 5).

Programs

  • Maple
    aList := upto -> local k; [seq(k/9, k in select(n -> add(convert(n, base, 3)) < padic[ordp](n, 3), [seq(9..upto,9)]))]: aList(9000);
  • Mathematica
    Select[Range[9000],DigitSum[#,3]Stefano Spezia, Mar 08 2025 *)
  • SageMath
    def aList(upto, b): return [n/b^2 for n in srange(b^2, upto, b^2) if sum(n.digits(b)) < valuation(n, b)]
    print(aList(9000, 3))

A381833 k/25 is in this list if k > 5 and A053824(k) = A112765(k), i.e. if digitsum(k, 5) = valuation(k, 5).

Original entry on oeis.org

2, 6, 15, 26, 35, 55, 100, 126, 135, 155, 200, 255, 300, 400, 626, 635, 655, 700, 755, 800, 900, 1125, 1255, 1300, 1400, 1625, 1900, 2125, 2625, 3126, 3135, 3155, 3200, 3255, 3300, 3400, 3625, 3755, 3800, 3900, 4125, 4400, 4625, 5125, 6255, 6300, 6400, 6625, 6900, 7125
Offset: 1

Views

Author

Peter Luschny, Mar 09 2025

Keywords

Crossrefs

Cf. A381835 (base = 3), A381834 (base = 4).

Programs

  • Mathematica
    Select[Range[25, 180000, 25], DigitSum[#, 5] == IntegerExponent[#, 5] &] / 25
Showing 1-3 of 3 results.