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.

A348179 Replace each decimal digit d of n with the digit that is d steps to the right of d. Interpret the digits of n as a cycle: one step to the right from the last digit is considered to be the first.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 11, 22, 31, 44, 51, 66, 71, 88, 91, 20, 22, 22, 22, 24, 22, 26, 22, 28, 22, 0, 13, 22, 33, 44, 53, 66, 73, 88, 93, 40, 44, 42, 44, 44, 44, 46, 44, 48, 44, 0, 15, 22, 35, 44, 55, 66, 75, 88, 95, 60, 66, 62, 66, 64, 66, 66, 66, 68, 66, 0, 17, 22, 37, 44, 57, 66, 77, 88, 97, 80, 88, 82, 88, 84, 88, 86, 88, 88, 88, 0, 19, 22, 39, 44, 59, 66, 79, 88, 99, 0, 1
Offset: 0

Views

Author

Sebastian Karlsson, Oct 05 2021

Keywords

Comments

First differs from A349422 at a(101). - Sebastian Karlsson, Dec 31 2021

Examples

			a(102345) = 004124 = 4124. For example, 4 gets replaced by 2 because moving 4 steps to the right gives: 4 -> 5 -> 1 -> 0 -> 2. Note that from 5 we went to the first digit of the number.

Links

Crossrefs

Cf. A336668 (fixed points), A349422 (to the left), A349423 (index of first appearance of n).
Cf. A106649, A139337, A322131, A339023, A341767, A341953, A346576, A347323.

Programs

  • Haskell
    import Data.Char (digitToInt)
a n = let s = show n; l = length s in
  read [s !! (mod (i + digitToInt (s !! i)) l) | i <- [0..l-1]] :: Integer
  • Mathematica
    Table[FromDigits@Table[v[[If[(p=Mod[k+v[[k]],t])==0,t,p]]],{k,t=Length[v=IntegerDigits[n]]}],{n,0,67}] (* Giorgos Kalogeropoulos, Oct 08 2021 *)
  • PARI
    f(k, d) = d[(k+d[k]-1)%#d + 1];
a(n) = my(d=digits(n), dd=vector(#d, k, f(k, d))); fromdigits(dd); \\ Michel Marcus, Oct 07 2021
  • Python
    def a(n):
    s, l = str(n), len(str(n))
    return int("".join(s[(i + int(s[i])) % l] for i in range(l)))

Extensions

a(68)-a(101) from Sebastian Karlsson, Dec 31 2021

A341767 Replace each digit d in the decimal representation of n with the digital root of n^d.

Original entry on oeis.org

1, 4, 9, 4, 2, 9, 7, 1, 9, 11, 22, 39, 41, 54, 69, 71, 88, 99, 11, 41, 93, 77, 78, 99, 44, 11, 99, 11, 48, 91, 14, 87, 99, 17, 88, 99, 11, 84, 99, 41, 45, 99, 71, 11, 99, 11, 72, 99, 41, 21, 96, 44, 88, 99, 11, 51, 99, 77, 28, 91, 17, 11, 99, 11, 15, 99, 14
Offset: 1

Views

Author

Sebastian Karlsson, Feb 19 2021

Keywords

Comments

If n == 1 (mod 9), then every digit will be replaced by "1". If n == 0 (mod 9), then all nonzero digits will be replaced by "9".
The corresponding n of values a(n)= 1, a(n)= 11, a(n)= 111,... creates a subsequence of A236653. - Davide Rotondo, Mar 04 2024

Examples

			a(26) = 11, since 26^2 = 676 and 26^6 = 308915776. 6 + 7 + 6 = 19, 1 + 9 = 10 and 1 + 0 = 1, so the digital root of 676 is 1. 3 + 0 + 8 + 9 + 1 + 5 + 7 + 7 + 6 = 46, 4 + 6 = 10 and 1 + 0 = 1, so the digital root of 308915776 is 1. Thus, for 26, both "2" and "6" will be replaced by "1".

Links

Crossrefs

Cf. A010888, A106649, A139337, A322131, A339023.

Programs

  • Mathematica
    a[n_] := FromDigits[Mod[n^IntegerDigits[n] - 1, 9] + 1]; Array[a, 100] (* Amiram Eldar, Feb 19 2021 *)
  • PARI
    dr(n) = if(n, (n-1)%9+1); \\ A010888
a(n) = my(d=digits(n)); fromdigits(vector(#d, k, dr(n^d[k]))); \\ Michel Marcus, Feb 19 2021
  • Python
    def a(n):
    return int(''.join(str((pow(n, int(d), 9)-1)%9 + 1) for d in str(n)))

Formula

a(10*n) = 10*a(n) + 1.

A341953 Replace each digit d in the decimal representation of n with the digital root of d^n.

Original entry on oeis.org

1, 4, 9, 4, 2, 9, 7, 1, 9, 10, 11, 11, 19, 17, 18, 19, 14, 11, 19, 40, 81, 77, 59, 11, 25, 49, 81, 71, 59, 90, 91, 94, 99, 94, 92, 99, 97, 91, 99, 40, 71, 11, 49, 77, 18, 49, 74, 11, 49, 70, 81, 47, 29, 11, 55, 79, 81, 41, 29, 90, 91, 94, 99, 94, 92, 99, 97
Offset: 1

Views

Author

Sebastian Karlsson, Feb 24 2021

Keywords

Comments

The digits 0, 1, 3, 6 and 9 will always be replaced by the same digits: 0 -> 0, 1 -> 1, 3 -> 9, 6 -> 9 and 9 -> 9.

Examples

			a(14) = 17, since 1^14 = 1 and 4^14 = 268435456. 2 + 6 + 8 + 4 + 3 + 5 + 4 + 5 + 6 = 43 and 4 + 3 = 7. Thus, the digital root of 268435456 is 7. This means that for 14, "1" gets replaced by "1" and "4" gets replaced by "7".

Links

Crossrefs

Cf. A010888, A106649, A139337, A322131, A339023, A341767.

Programs

  • Mathematica
    digroot[n_] := If[n == 0, 0, Mod[n - 1, 9] + 1]; a[n_] := FromDigits[digroot /@ (IntegerDigits[n]^n)]; Array[a, 100] (* Amiram Eldar, Feb 24 2021 *)
  • PARI
    r(n) = if(n, (n-1)%9+1) \\ A010888
a(n) = fromdigits(apply(x->r(x^n), digits(n))); \\ Michel Marcus, Mar 21 2021
  • Python
    def D(d, n):
    return 0 if d == 0 else (pow(d, n, 9)-1)%9 + 1
def a(n):
    return int(''.join(str(D(int(d), n)) for d in str(n)))
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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