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 1-4 of 4 results.

A036507 Smallest square containing exactly n decimal digits '0'.

Original entry on oeis.org

0, 100, 102400, 10000, 10240000, 1000000, 1024000000, 100000000, 102400000000, 10000000000, 10240000000000, 1000000000000, 1024000000000000, 100000000000000, 102400000000000000, 10000000000000000, 10240000000000000000, 1000000000000000000, 1024000000000000000000
Offset: 1

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Author

Keywords

Crossrefs

Cf. A036508 (digits 1), A036509 (2), A036510 (3), A036511 (4), A036512 (5), A036513 (6), A036514 (7), A036515 (8), A036516 (9).

Programs

  • Mathematica
    nsmall = Table[Infinity, 20];
    For[i = 0, i <= 4*10^6, i++, n0 = Count[IntegerDigits[i^2], 0];
      If[nsmall[[n0]] > i^2, nsmall[[n0]] = i^2]];
    ReplaceAll[nsmall, Infinity -> "?"] (* Robert Price, Mar 22 2020 *)
    a[n_] := If[OddQ[n], 1024*10^(n-1), 10^n]; a[1] = 0; Array[a, 20] (* Amiram Eldar, Aug 26 2025 *)

Formula

a(2*n) = 10^(2*n), a(2*n+1) = 1024*10^(2*n) for n >= 1 since 1024 is the smallest square factor that contains a single '0'. - Georg Fischer, Jul 03 2023
Sum_{n>=2} 1/a(n) = 1025/101376. - Amiram Eldar, Aug 26 2025

A036533 Smallest cube containing exactly n 6's.

Original entry on oeis.org

0, 64, 166375, 46656, 367061696, 1676676672, 66676466375, 2646396666368, 6666963601661, 6946660616126616, 3666676156163166167, 62656677666653866496, 2674826866666660366016, 166465666639716668628669, 3656365366626065666266624, 167947668303666616666566656
Offset: 0

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Author

Keywords

Comments

a(n)^(1/3) = A048371(n) is the index of the first occurrence of n in sequence A269246. - M. F. Hasler, Feb 21 2016

Crossrefs

Cf. A048371, A036527 - A036536 for other digits 0 - 9.
Analog for squares: A036510 = A048348^2.

Programs

  • Mathematica
    nsmall = Table[Infinity, 20];
    For[i = 0, i <= 10^6, i++, n0 = Count[IntegerDigits[i^3], 6];
      If[nsmall[[n0 + 1]] > i^3, nsmall[[n0 + 1]] = i^3]];
    Cases[nsmall, ?NumberQ] (* _Robert Price, Mar 21 2020 *)

Formula

a(n) = A048371(n)^3. - M. F. Hasler, Feb 21 2016

Extensions

Extended with a(0) = 0 by M. F. Hasler, Feb 21 2016
a(11)-a(15) from Giovanni Resta, Jun 29 2018

A048348 a(n)^2 is the smallest square containing exactly n 3's.

Original entry on oeis.org

6, 56, 586, 1156, 11547, 57735, 559769, 1197219, 6582806, 36514844, 350903624, 1798230611, 1825769244, 48304278624, 11547014044, 577333277556, 1527394295306, 6582576498844, 57465931849517, 416333244448889, 581664313273844, 4820096824065156, 18256870415638994, 61913999493598646, 577694870440557344
Offset: 1

Views

Author

Patrick De Geest, Mar 15 1999

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 3] != n, k++]; k]; Array[a, 6] (* Giovanni Resta, Jul 27 2018 *)

Extensions

More terms from Jon E. Schoenfield, Jan 11 2009
a(18)-a(19) from Giovanni Resta, Jul 27 2018
a(20)-a(25) from Max Alekseyev, Mar 06 2025

A137434 a(n) = smallest square containing n copies of the same nonzero digit.

Original entry on oeis.org

1, 121, 1444, 44944, 6441444, 47444544, 4434494464, 44424414441, 1113111511681, 22222220262025, 444431244445444, 22292262226224225, 441544444344443449, 1113101111111117041, 2222222222222640225, 11111119101145491111121
Offset: 1

Views

Author

Randy L. Ekl, Apr 17 2008

Keywords

Examples

			a(9) = 1113111511681 because there is no smaller square number with 9 copies of the same nonzero digit. a(9) has 9 1's.
		

Crossrefs

Extensions

Edited by N. J. A. Sloane at the suggestion of Jon E. Schoenfield, Jan 11 2009
a(12)-a(15) from Jon E. Schoenfield, Jan 14 2009
a(16) from Jon E. Schoenfield, Jan 17 2009
Showing 1-4 of 4 results.