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.

A059805 Natural numbers written with digits grouped in pairs and leading zeros omitted.

Original entry on oeis.org

12, 34, 56, 78, 91, 1, 11, 21, 31, 41, 51, 61, 71, 81, 92, 2, 12, 22, 32, 42, 52, 62, 72, 82, 93, 3, 13, 23, 33, 43, 53, 63, 73, 83, 94, 4, 14, 24, 34, 44, 54, 64, 74, 84, 95, 5, 15, 25, 35, 45, 55, 65, 75, 85, 96, 6, 16, 26, 36, 46, 56, 66, 76, 86, 97, 7, 17, 27, 37, 47, 57, 67
Offset: 1

Views

Author

Kazimierz Kurz (kurzk(AT)prokom.pl), Mar 01 2001

Keywords

Links

Crossrefs

Cf. A000027, A087406, A060936, A087407, A087408, A087409, A087075, A087410, A087411.
Cf. A091331, A091332.

Programs

  • Mathematica
    FromDigits /@ Partition[ Flatten[ IntegerDigits[ Table[ n, {n, 1, 77}]]], 2] (* Robert G. Wilson v *)
FromDigits/@Partition[Flatten[IntegerDigits/@Range[100]],2] (* Harvey P. Dale, Feb 13 2025 *)
  • PARI
    {c=0; d=[]; for(n=1, 99, while(#d<2, d=concat(d, digits(c++))); print1(d[1],d[2]", "); d=vecextract(d, "^..2"))} \\ M. F. Hasler, Oct 23 2014

Formula

a(2n-1)*100 + a(2n) = A091332(n); a(2n-1) = floor(A091332(n)/100), a(2n) = (A091332(n) mod 100). - M. F. Hasler, Oct 23 2014

Extensions

More terms from Jason Earls, Mar 24 2001

A091332 Natural numbers written out with their digits grouped in sets of four (leading zeros omitted).

Original entry on oeis.org

1234, 5678, 9101, 1121, 3141, 5161, 7181, 9202, 1222, 3242, 5262, 7282, 9303, 1323, 3343, 5363, 7383, 9404, 1424, 3444, 5464, 7484, 9505, 1525, 3545, 5565, 7585, 9606, 1626, 3646, 5666, 7686, 9707, 1727, 3747, 5767, 7787, 9808, 1828, 3848, 5868, 7888
Offset: 1

Views

Author

J. Taylor (integersfan(AT)yahoo.com), Mar 01 2004

Keywords

Links

Crossrefs

Cf. A059805, A091331.

Programs

  • PARI
    {c=0; d=[]; for(n=1, 99, while(#d<4, d=concat(d, digits(c++))); print1(sum(i=1,4,d[i]*10^(4-i))", "); d=vecextract(d, "^..4"))} \\ M. F. Hasler, Oct 23 2014

A248556 Concatenate (3n-2,3n-1,3n).

Original entry on oeis.org

123, 456, 789, 101112, 131415, 161718, 192021, 222324, 252627, 282930, 313233, 343536, 373839, 404142, 434445, 464748, 495051, 525354, 555657, 585960, 616263, 646566, 676869, 707172, 737475, 767778, 798081, 828384, 858687, 888990, 919293, 949596, 979899
Offset: 1

Views

Author

Charles Duvall, Oct 08 2014

Keywords

Crossrefs

Cf. A030655, A091331.

Programs

  • Magma
    [Seqint(Intseq(n+1) cat Intseq(n) cat Intseq(n-1)): n in [2..100 by 3]]; // Vincenzo Librandi, Oct 21 2014
  • Maple
    conc3:= (a,b,c) -> c + 10^(1+ilog10(c))*(b+10^(1+ilog10(b))*a):
seq(conc3(3*k-2,3*k-1,3*k), k=1..100); # Robert Israel, Oct 23 2014
  • Mathematica
    FromDigits[Flatten[IntegerDigits/@{#}]]&/@Partition[Range[100], 3] (* Vincenzo Librandi, Oct 21 2014 *)
  • PARI
    a(n)=eval(Str(3*n-2,3*n-1,3*n)) \\ M. F. Hasler, Oct 22 2014

Extensions

More terms from Vincenzo Librandi, Oct 21 2014

A249182 Proceed counterclockwise on the outer keys of a numeric keypad (i.e., 1,2,3,6,9,8,7,4): first single digits, then concatenate two digits, then three, etc.

Original entry on oeis.org

1, 2, 3, 6, 9, 8, 7, 4, 12, 23, 36, 69, 98, 87, 74, 41, 123, 236, 369, 698, 987, 874, 741, 412, 1236, 2369, 3698, 6987, 9874, 8741, 7412, 4123, 12369, 23698, 36987, 69874, 98741, 87412, 74123, 41236, 123698, 236987, 369874, 698741, 987412, 874123, 741236, 412369
Offset: 1

Views

Author

M. F. Hasler, Oct 23 2014

Keywords

Comments

k-digit terms start at index 8k-7; for example, at index 57, start the 8-digit terms 12369874, 23698741, 36987412, 69874123, 98741236, 87412369, 74123698, 41236987.

Crossrefs

Cf. A059805, A091331, A091332, A249163.

Programs

  • PARI
    d=Vec("12369874");for(L=1,6,for(i=1,#d,print1(concat(vector(L,j,d[(i+j-2)%#d+1]))",")))
Showing 1-4 of 4 results.

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

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