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 1-6 of 6 results.

A062028 a(n) = n + sum of the digits of n.

Original entry on oeis.org

0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 77
Offset: 0

Views

Author

Amarnath Murthy, Jun 02 2001

Keywords

Comments

a(n) = A248110(n,A007953(n)). - Reinhard Zumkeller, Oct 01 2014

Examples

			a(34) = 34 + 3 + 4 = 41, a(40) = 40 + 4 = 44.
		

Crossrefs

Indices of: A047791 (primes), A107743 (composites), A066564 (squares), A084661 (cubes).
Iterations: A004207 (start=1), A016052 (start=3), A007618 (start=5), A006507 (start=7), A016096 (start=9).

Programs

  • Haskell
    a062028 n = a007953 n + n  -- Reinhard Zumkeller, Oct 11 2013
    
  • Maple
    with(numtheory): for n from 1 to 100 do a := convert(n,base,10):
    c := add(a[i],i=1..nops(a)): printf(`%d,`,n+c); od:
    A062028 := n -> n+add(i,i=convert(n,base,10)) # M. F. Hasler, Nov 08 2018
  • Mathematica
    Table[n + Total[IntegerDigits[n]], {n, 0, 100}]
  • PARI
    A062028(n)=n+sumdigits(n) \\ M. F. Hasler, Jul 19 2015
    
  • Python
    def a(n): return n + sum(map(int, str(n)))
    print([a(n) for n in range(71)]) # Michael S. Branicky, Jan 09 2023

Formula

a(n) = n + A007953(n).
a(n) = A160939(n+1) - 1. - Filip Zaludek, Oct 26 2016

Extensions

More terms from Vladeta Jovovic, Jun 05 2001

A007612 a(n+1) = a(n) + digital root (A010888) of a(n).

Original entry on oeis.org

1, 2, 4, 8, 16, 23, 28, 29, 31, 35, 43, 50, 55, 56, 58, 62, 70, 77, 82, 83, 85, 89, 97, 104, 109, 110, 112, 116, 124, 131, 136, 137, 139, 143, 151, 158, 163, 164, 166, 170, 178, 185, 190, 191, 193, 197, 205, 212, 217, 218, 220, 224, 232, 239, 244, 245, 247, 251
Offset: 1

Views

Author

Keywords

Comments

Take m, a natural number. If m == 1 (mod 6), then for every n a(m)*a(n) is in A007612. - Ivan N. Ianakiev, May 08 2013

References

  • J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 65.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Haskell
    a007612 n = a007612_list !! (n-1)
    a007612_list = iterate a064806 1  -- Reinhard Zumkeller, Apr 13 2013
    
  • Maple
    A007612 := proc(n) option remember: if(n=1)then return 1: fi: return procname(n-1) + ((procname(n-1)-1) mod 9) + 1: end: seq(A007612(n), n=1..100); # Nathaniel Johnston, May 04 2011
  • Mathematica
    dr[n_]:=NestWhile[Total[IntegerDigits[#]]&,n,#>9&]; NestList[#+dr[#]&, 1,60] (* Harvey P. Dale, Sep 24 2011 *)
    NestList[#+Mod[#,9]&,1,60] (* Harvey P. Dale, Sep 14 2016 *)
  • PARI
    first(n)=my(v=vector(n)); v[1]=1; for(k=2,n, v[k]=v[k-1]+v[k-1]%9); v \\ Charles R Greathouse IV, Jun 25 2017
    
  • PARI
    a(n)=n\6*27 + [-4,1,2,4,8,16][n%6+1] \\ Charles R Greathouse IV, Jun 25 2017

Formula

a(1) = 1, a(n+1) = a(n) + a(n) mod 9. - Reinhard Zumkeller, Mar 23 2003
First differences are [1,2,4,8,7,5] repeated. - M. F. Hasler, Sep 15 2009; corrected by John Keith, Aug 17 2022
n == 1, 2, 4, 8, 16, or 23 (mod 27). - Dean Hickerson, Mar 25 2003
Limit_{n->oo} a(n)/n = 9/2; A029898(n) = a(n+1) - a(n) = A010888(a(n)). - Reinhard Zumkeller, Feb 27 2006
a(6n+1)=27n+1, a(6n+2)=27n+2, a(6n+3)=27n+4, a(6n+4)=27n+8, a(6n+5)=27n+16, a(6n+6)=27n+23. - Franklin T. Adams-Watters, Mar 13 2006
G.f.: (1+4*x^4+3*x^3+x^2)/((x+1)*(x^2-x+1)*(x-1)^2). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 10 2009
a(n+1) = A064806(a(n)). - Reinhard Zumkeller, Apr 13 2013

A108773 Concatenation of n and the sum of the digits of n.

Original entry on oeis.org

0, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 112, 123, 134, 145, 156, 167, 178, 189, 1910, 202, 213, 224, 235, 246, 257, 268, 279, 2810, 2911, 303, 314, 325, 336, 347, 358, 369, 3710, 3811, 3912, 404, 415, 426, 437, 448, 459, 4610, 4711, 4812, 4913, 505, 516, 527
Offset: 0

Views

Author

N. J. A. Sloane, Jun 26 2005

Keywords

Comments

A136614(n) = A007953(a(n)) = A007953(A136613(n)). - Reinhard Zumkeller, Jan 13 2008

Crossrefs

Programs

  • Mathematica
    f[n_] := FromDigits[ Join[ IntegerDigits[n], IntegerDigits[Plus @@ IntegerDigits[n]]]]; Table[ f[n], {n, 0, 52}] (* Robert G. Wilson v, Jun 28 2005 *)
  • PARI
    a(n) = eval(concat(Str(n), Str(sumdigits(n)))); \\ Michel Marcus, Nov 12 2023

Extensions

More terms from Robert G. Wilson v, Jun 28 2005

A177274 Periodic sequence: Repeat 1, 2, 3, 4, 5, 6, 7, 8, 9.

Original entry on oeis.org

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

Views

Author

Klaus Brockhaus, May 07 2010

Keywords

Comments

Interleaving of A131669 and A131669 without first five terms.
Continued fraction expansion of (684125+sqrt(635918528029))/1033802.
Decimal expansion of 13717421/111111111.
a(n) = A010888(n+1) = A010878(n)+1 = A117230(n+2)-1.
a(n) = A064806(n+1)-n-1.
Essentially first differences of A037123.

Crossrefs

Cf. A131669 (odd digits followed by positive even digits), A010888 (digital root of n), A010878 (n mod 9), A117230 (1 followed by (repeat 2, 3, 4, 5, 6, 7, 8, 9, 10), offset 1), A064806 (n + digital root of n), A037123, A177270 (decimal expansion of (684125+sqrt(635918528029))/1033802).

Programs

  • Magma
    &cat[ [1, 2, 3, 4, 5, 6, 7, 8, 9]: k in [1..12] ];
  • Mathematica
    PadRight[{},120,Range[9]] (* Paolo Xausa, Jan 08 2024 *)

Formula

a(n) = (n mod 9)+1.
a(n) = a(n-9) for n > 8; 1; a(n) = n+1 for n <= 8.
G.f.: (1+2*x+3*x^2+4*x^3+5*x^4+6*x^5+7*x^6+8*x^7+9*x^8)/(1-x^9). [corrected by Georg Fischer, May 11 2019]

A108203 Numbers n put into lexicographical order which are the concatenation of k and the sum of the digits of k.

Original entry on oeis.org

11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 112, 123, 134, 145, 156, 167, 178, 189, 202, 213, 224, 235, 246, 257, 268, 279, 303, 314, 325, 336, 347, 358, 369, 404, 415, 426, 437, 448, 459, 505, 516, 527, 538, 549, 606, 617, 628, 639, 707, 718, 729, 808, 819, 909, 1001
Offset: 1

Views

Author

Keywords

Examples

			1 --> 11, 2 --> 22, 3 --> 33, ..., 9 --> 99, 10 --> 101, 11 --> 112, 12 --> 123,
..., 18 --> 189, 19 --> 1910 (ouch!), 20 --> 202, 21 --> 213, ...
		

Crossrefs

Cf. A062028, A064806. Equals A108773 sorted.

Programs

  • Mathematica
    f[n_] := FromDigits[ Join[ IntegerDigits[ n], IntegerDigits[Plus @@ IntegerDigits[ n]] ]]; t = {}; Do[t = Union[AppendTo[t, f[n]]], {n, 10^6}]

Extensions

a(55) from Rémy Sigrist, May 16 2019

A253610 Numbers n with property that the sum of n and the digital root of n is prime.

Original entry on oeis.org

1, 10, 11, 13, 14, 16, 28, 29, 32, 34, 35, 46, 49, 52, 53, 65, 67, 68, 71, 82, 85, 89, 100, 101, 103, 104, 106, 122, 124, 136, 137, 142, 143, 155, 158, 160, 172, 175, 176, 190, 191, 193, 194, 209, 215, 226, 227, 229, 232, 233, 247, 250, 262, 265, 266, 269, 280
Offset: 1

Views

Author

Robert Gelhar, Jan 05 2015

Keywords

Comments

Indices of primes in A064806. - Tom Edgar, Jan 07 2015
For any prime p >= 11, if p == k mod 9 then n = p - k/2 (if k is even) or p - (k+9)/2 (if k is odd) is in the sequence. - Robert Israel, Jan 07 2015

Crossrefs

Programs

  • Magma
    [n: n in [1..300]| IsPrime(n+(1+(n-1)mod 9))]; // Vincenzo Librandi, Jan 15 2015
  • Maple
    map(p -> p - (p/2 mod 9), [2, seq(ithprime(i), i=5..100)]); # Robert Israel, Jan 07 2015
  • Mathematica
    Select[Range[100],PrimeQ[#+Mod[#,9]]&] (* Ivan N. Ianakiev, Feb 01 2015 *)
  • Sage
    [n for n in [1..200] if is_prime(n+(1+(n-1)%9))] # Tom Edgar, Jan 05 2015
    
Showing 1-6 of 6 results.