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.

A083822 a(n) = digit reversal of 3*n, divided by 3.

Original entry on oeis.org

1, 2, 3, 7, 17, 27, 4, 14, 24, 1, 11, 21, 31, 8, 18, 28, 5, 15, 25, 2, 12, 22, 32, 9, 19, 29, 6, 16, 26, 3, 13, 23, 33, 67, 167, 267, 37, 137, 237, 7, 107, 207, 307, 77, 177, 277, 47, 147, 247, 17, 117, 217, 317, 87, 187, 287, 57, 157, 257, 27, 127, 227, 327, 97, 197, 297, 34
Offset: 1

Views

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003

Keywords

Comments

If n is a multiple of 10, then a(n) = a(n/10); if n is not a multiple of 10, then a(a(n)) = n.

Examples

			a(25) = reverse(3*25)/3 = reverse(75)/3 = 57/3 = 19.
		

Crossrefs

Programs

  • Mathematica
    Table[FromDigits[Reverse[IntegerDigits[3n]]]/3,{n,70}] (* Harvey P. Dale, May 19 2015 *)
    IntegerReverse[3*Range[70]]/3 (* Harvey P. Dale, Apr 12 2022 *)
  • PARI
    {for(n=1,70,k=3*n; rev=0; while(k>0,d=divrem(k,10); k=d[1]; rev=10*rev+d[2]); print1(rev/3,","))}
    
  • PARI
    apply( A083822(n)=fromdigits(Vecrev(digits(3*n)))/3, [0..99]) \\ M. F. Hasler, May 21 2021

Extensions

Edited, corrected and extended by Klaus Brockhaus, May 11 2003

A083824 a(n) = digit reversal of 9*n, divided by 9.

Original entry on oeis.org

0, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 11, 89, 79, 69, 59, 49, 39, 29, 19, 9, 109, 99, 78, 68, 58, 48, 38, 28, 18, 8, 108, 98, 88, 67, 57, 47, 37, 27, 17, 7, 107, 97, 87, 77, 56, 46, 36, 26, 16, 6, 106, 96, 86, 76, 66, 45, 35, 25, 15, 5, 105, 95, 85, 75, 65, 55, 34, 24, 14, 4, 104, 94, 84
Offset: 0

Views

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003

Keywords

Comments

If n is a multiple of 10, then a(n) = a(n/10); if n is not a multiple of 10, then a(a(n)) = n.

Examples

			a(2) = reverse(9*2)/9 = reverse(18)/9 = 81/9 = 9.
		

Crossrefs

Cf. A083822 (analog for 3), A083823, A083825.

Programs

  • PARI
    {for(n=0,73,k=9*n; rev=0; while(k>0,d=divrem(k,10); k=d[1]; rev=10*rev+d[2]); print1(rev/9,","))}
    
  • PARI
    apply( {A083824(n)=fromdigits(Vecrev(digits(9*n)))/9}, [0..99]) \\ M. F. Hasler, May 21 2021

Extensions

Edited, corrected and extended by Klaus Brockhaus, May 11 2003
Minor edits and extension to offset 0 by M. F. Hasler, May 21 2021

A083823 a(1) = 15; then numbers obtained at every stage of division by 3 in the following process: multiply by 3, reverse the digits, divide by 3, reverse the digits, multiply by 3, reverse the digit, divide by 3.

Original entry on oeis.org

15, 18, 114, 1107, 11004, 110007, 1100004, 11000007, 110000004, 1100000007, 11000000004, 110000000007, 1100000000004, 11000000000007, 110000000000004, 1100000000000007, 11000000000000004, 110000000000000007, 1100000000000000004, 11000000000000000007
Offset: 1

Views

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003

Keywords

Comments

1. 15 is the smallest number which does not follow a cyclic pattern or terminates at k < 10. 2. A pattern is visible. For 12 one gets the cyclic pattern 12->36->63->21->12->36... for 14 one gets 14 ->42->24->8->8... Subsidiary sequences that could be considered: (1) Sequence of numbers which show cyclic pattern. (2) Sequence of numbers which terminate at k,k <10. (3) Numbers which gare not members of (1) and (2).

Examples

			*15->45->54->*18->81->243->342->*114->411->1233->3321->*1107->7011->21033->33012->*11004->
Numbers marked with * are members.
		

Crossrefs

Showing 1-3 of 3 results.