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.

A069599 Duplicate of A088628.

Original entry on oeis.org

11, 127, 1123, 1423, 112543, 1124653, 1234657, 112345687, 1234156789, 10124356789
Offset: 1

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Author

Keywords

A069600 Smallest square containing all the digits of numbers from 1 to n. For a(10) and higher, all duplicated digits must be in the term (for example a(10) has two 1's).

Original entry on oeis.org

1, 121, 3721, 13924, 135424, 1236544, 13527684, 13527684, 139854276, 11738205649, 10112819764356, 1011123678945241, 10118426359171321, 10111134329645378121, 1011111632116847554329, 10111124953183456116721, 1011111119736855441726321, 101111112641746351915327881, 10111111111271587168434259369
Offset: 1

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Author

Amarnath Murthy, Mar 25 2002

Keywords

Examples

			a(5) = 335241 = 579^2 contains digits 1,2,3,4 and 5.
		

Crossrefs

Cf. A088628.

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jan 20 2003
a(14)-a(15) from Giovanni Resta, Aug 06 2019
a(16)-a(19) from Chai Wah Wu, May 18 2020

A069601 Smallest triangular number containing all the digits of numbers from 1 to n.

Original entry on oeis.org

1, 21, 231, 12403, 24531, 235641, 2467531, 13862745, 153694278, 10429651378, 1017139458621, 101114872391625, 10111496127133528, 1011137441915312286, 101111293764315411825, 10111111491815764232356, 1011111155214617733491628, 101111111617874325294116835
Offset: 1

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Author

Amarnath Murthy, Mar 25 2002

Keywords

Comments

For a(10) and higher, all duplicated digits must be in the term (for example a(10) has two 1's).
Conjecture: except for a(4), the digits of a(n) are exactly all the digits of numbers from 1 to n. - Chai Wah Wu, May 18 2020

Examples

			a(5) = 219453 = T(662) contains digits 1, 2, 3, 4 and 5.
		

Crossrefs

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jan 24 2003
a(15)-a(18) from Chai Wah Wu, May 18 2020

A332265 a(n) is the number of prime numbers created when concatenating all the arrangements of the decimal integers from 0 to 3*n+4.

Original entry on oeis.org

20, 3202, 2056675, 3500185228
Offset: 0

Views

Author

Scott R. Shannon, May 04 2020

Keywords

Comments

Only 4 and every third integer after 4 can create primes when concatenating the integer arrangements of 0,...,3*n+4 as the other integer values will create numbers with digit sums divisible by 3, and hence are divisible by 3. The digit 0 is allowed to be the first digit in the number but is then ignored when determining if the remaining digits form a prime.

Examples

			a(0) = 20 as there are twenty primes created when concatenating the integer arrangements of 0,1,2,3,4. They are 1423, 2143, 2341, 4231, 10243, 12043, 20143, 20341, 20431, 23041, 24103, 30241, 32401, 40123, 40213, 40231, 41023, 41203, 42013, 43201.
a(1) = 3202. The smallest prime created using integers 0..7 is 1234657 while the largest is 76540231.
a(2) = 2056675. The smallest prime created using integers 0..10 is 10123457689 while the largest is 987654310021.
		

Crossrefs

Programs

  • Mathematica
    Table[Count[FromDigits /@  Flatten /@ IntegerDigits /@ Permutations[Range[0, 3 n + 4]], ?PrimeQ], {n, 0, 2}] (* _Robert Price, Sep 16 2020 *)
    (* OR, if the above runs low on memory to store all the Permutations at once... *)
    Table[p0 = Range[0, 3n+4]; p = NextPermutation[p0]; c = 0;
     While[p != p0,
      If[PrimeQ[FromDigits[Flatten[IntegerDigits /@ p]]], c++];
    p = NextPermutation[p]]; c, {n, 0, 2}] (* Robert Price, Sep 16 2020 *)

Extensions

a(3) from Giovanni Resta, May 04 2020
Showing 1-4 of 4 results.