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.

A179051 Number of partitions of n into powers of 10 (cf. A011557).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10
Offset: 0

Views

Author

Reinhard Zumkeller, Jun 27 2010

Keywords

Comments

A179052 and A008592 give record values and where they occur.

Examples

			a(19) = #{10 + 9x1, 19x1} = 2;
a(20) = #{10 + 10, 10 + 10x1, 20x1} = 3;
a(21) = #{10 + 10 + 1, 10 + 11x1, 21x1} = 3.
		

Crossrefs

Number of partitions of n into powers of b: A018819 (b=2), A062051 (b=3).

Programs

  • Haskell
    a179051 = p 1 where
       p _ 0 = 1
       p k m = if m < k then 0 else p k (m - k) + p (k * 10) m
    -- Reinhard Zumkeller, Feb 05 2012
  • Mathematica
    terms = 10001;
    CoefficientList[Product[1/(1 - x^(10^k)) + O[x]^terms,
         {k, 0, Log[10, terms] // Ceiling}], x]
    (* Jean-François Alcover, Dec 12 2021, after Ilya Gutkovskiy *)

Formula

a(n) = A133880(n) for n < 90; a(n) = A132272(n) for n < 100.
a(10^n) = A145513(n).
a(10*n) = A179052(n).
A179052(n) = a(A008592(n));
a(n) = p(n,1) where p(n,k) = if k<=n then p(10*[(n-k)/10],k)+p(n,10*k) else 0^n.
G.f.: Product_{k>=0} 1/(1 - x^(10^k)). - Ilya Gutkovskiy, Jul 26 2017

A083278 Repunit powers.

Original entry on oeis.org

1, 11, 111, 121, 1111, 1331, 11111, 12321, 14641, 111111, 161051, 1111111, 1234321, 1367631, 1771561, 11111111, 19487171, 111111111, 123454321, 151807041, 214358881, 1111111111, 1371330631, 2357947691, 11111111111
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 02 2003

Keywords

Examples

			a(13)=1234321=1111^2; a(14)=1367631=111^3; a(15)=1771561=11^6.
		

Crossrefs

Programs

  • Haskell
    import Data.Set (empty, findMin, deleteMin, deleteMin, insert)
    import qualified Data.Set as Set (null)
    a083278 n = a083278_list !! (n-1)
    a083278_list = 1 : f empty (drop 2 a002275_list) where
       f rups rus'@(ru:rus)
         | Set.null rups || m > ru = f (insert (ru,ru) rups) rus
         | otherwise = m : f (insert (m*m',m') (deleteMin rups)) rus'
         where (m,m') = findMin rups
    -- Reinhard Zumkeller, Feb 05 2012
    
  • Mathematica
    With[{intlen=12},Select[Union[Flatten[#^Range[intlen]&/@(FromDigits/@ Table[ PadRight[{},n,1],{n,intlen}])]],IntegerLength[#]<=intlen&]] (* Harvey P. Dale, Apr 25 2016 *)
  • PARI
    lista(nn) = {my(list = List(), r); for (n=1, nn, my(r = (10^n-1)/9); listput(list, r); if (r > 1, my(e=2); while(#Str(x=r^e) <= nn, listput(list, x); e++));); Vec(vecsort(list));} \\ Michel Marcus, May 28 2019

A206244 Number of partitions of n into repunits (A002275).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8
Offset: 0

Views

Author

Reinhard Zumkeller, Feb 05 2012

Keywords

Comments

a(n) = A206245(n) for n <= 120, a(n) < A206245(n) for n > 120.

Examples

			a(12)=2 is the first nontrivial term, from the partitions 12 = 1+1+...+1 = 11+1. - _N. J. A. Sloane_, Jul 26 2017
		

Crossrefs

Programs

  • Haskell
    a206244 = p $ tail a002275_list where
       p _             0 = 1
       p rus'@(ru:rus) n = if n < ru then 0 else p rus' (n - ru) + p rus n
  • Mathematica
    With[{nn = 50}, Table[Count[IntegerPartitions@ n, k_ /; ContainsAll[Array[Floor[10^#/9] &, IntegerLength[nn + 1]], Union@ k]], {n, 0, nn}]] (* Michael De Vlieger, Jul 26 2017 *)

Formula

G.f.: Product_{k>=1} 1/(1 - x^((10^k-1)/9)). - Ilya Gutkovskiy, Jul 26 2017
Showing 1-3 of 3 results.