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.

A275953 First differences of A265906; second differences of A265905.

Original entry on oeis.org

6, 30, 204, 1446, 11550, 108204, 1091526, 11998830, 146864484, 1920044166, 26872081230, 407766664284, 6548790510726, 111305007240510, 2018907373622004, 38462931870864486, 769155464685741870, 16240360254478668204, 358012008058965575046, 8233510983226617823230, 198405453050668260272364, 4967948949777295176374646, 129158062469199137001844830
Offset: 1

Views

Author

Antti Karttunen, Aug 13 2016

Keywords

Crossrefs

Row 3 of A275950.

Programs

Formula

a(n) = A265906(1+n) - A265906(n).

A275950 Square array A(1,k) = A265905(k), A(n>1,k) = A(n-1, k+1) - A(n-1, k); successive differences of A265905 read by descending antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), ...

Original entry on oeis.org

1, 3, 2, 11, 8, 6, 49, 38, 30, 24, 291, 242, 204, 174, 150, 1979, 1688, 1446, 1242, 1068, 918, 15217, 13238, 11550, 10104, 8862, 7794, 6876, 136659, 121442, 108204, 96654, 86550, 77688, 69894, 63018, 1349627, 1212968, 1091526, 983322, 886668, 800118, 722430, 652536, 589518, 14561425, 13211798, 11998830, 10907304, 9923982, 9037314, 8237196, 7514766, 6862230, 6272712
Offset: 1

Views

Author

Antti Karttunen, Aug 13 2016

Keywords

Examples

			The top left 7 x 8 corner of the array:
      1, 3, 11, 49, 291, 1979, 15217
      2, 8, 38, 242, 1688, 13238, 121442
      6, 30, 204, 1446, 11550, 108204, 1091526
     24, 174, 1242, 10104, 96654, 983322, 10907304
    150, 1068, 8862, 86550, 886668, 9923982, 123958350
    918, 7794, 77688, 800118, 9037314, 114034368, 1514355678
   6876, 69894, 722430, 8237196, 104997054, 1400321310, 20026187676
  63018, 652536, 7514766, 96759858, 1295324256, 18625866366, 291196957578
		

Crossrefs

Transpose: A275951.
Row 1: A265905, row 2: A265906, row 3: A275953.
Column 1: A275955.
Cf. A153880.
Variant: A275960.

Programs

Formula

A(1,k) = A265905(k); and for n > 1, A(n,k) = A(n-1, k+1) - A(n-1, k).

A265905 a(1) = 1; for n > 1, a(n) = a(n-1) + A153880(a(n-1)).

Original entry on oeis.org

1, 3, 11, 49, 291, 1979, 15217, 136659, 1349627, 14561425, 174637707, 2254758155, 31206959833, 467925825795, 7453435202483, 125743951819681, 2262941842058883, 42863071603162571, 852618666050008129, 17902734514975521891, 392964858422866610699, 9001537965557375522737, 216015564123360144707139, 5390978540058458090266187
Offset: 1

Views

Author

Antti Karttunen, Dec 20 2015

Keywords

Comments

In factorial base (A007623) these numbers look as:
1, 11, 121, 2001, 22011, 242121, 3004001, 33044011, 363524121, 4011111001, 44122221011, 485344431121, 5018801043001, , ...
This sequence is obtained by setting a(1) = 1, and then adding to each previous term a(n-1) the same factorial-base representation, but shifted by one factorial digit left. Only when a term does not contain any adjacent nonzero digits, as is the case with a(4) = "2001" or a(7) = "3004001", does the next term a(5) = "22011" (or respectively a(8) = "33044011") show the uncorrupted "double vision pattern". In other cases, for example, when going from a(2) to a(3), "11" to "121", two nonzero digits are summed up and there is possibly also a carry digit propagating to the left.
Note that the sequence is computed in such a way that factorial-base digits larger than 9 are also correctly summed together. That is, the eventual decimal corruption present in sequences like A007623 does not affect the actual values of this sequence. (See the implementation of A153880.)

Crossrefs

Row 1 of A275950.
Binomial transform of A275955 (when both are considered as offset-0 sequences).
Cf. A084558 (left inverse), A153880.
Cf. A001710, A265906 (first differences), A265907 (variant).

Programs

  • Mathematica
    f[n_] := Module[{k = n, m = 2, r, s = {0}}, While[{k, r} = QuotientRemainder[k, m]; k != 0 || r != 0, AppendTo[s, r]; m++]; FromDigits[Reverse[s], MixedRadix[Reverse@ Range[2, Length[s] + 1]]]]; NestList[f[#] + # &, 1, 23] (* Amiram Eldar, Feb 14 2024 *)

Formula

a(1) = 1; for n > 1, a(n) = a(n-1) + A153880(a(n-1)).
Other identities. For all n >= 1:
A084558(a(n)) = n. [The length of the factorial-base representation of the n-th term is always n.]

Extensions

Comment and the note about binomial transform corrected - Antti Karttunen, Sep 20 2016

A265908 a(n) = A255411(A265907(n)); also the first differences of A265907.

Original entry on oeis.org

4, 22, 256, 2500, 24598, 262192, 3005356, 36562174, 478487968, 12927533332, 280630789030, 5778343352464, 118583043104764, 2476606038823342, 53484469903211776, 1188931280602126420, 27430026590262346558, 653821165282804596712, 16172901278558141600116, 413537682797697142621894, 10959122779052635897843288, 300659352550430117464479652
Offset: 1

Views

Author

Antti Karttunen, Dec 20 2015

Keywords

Comments

In factorial base (A007623) these numbers are almost just like those of A265906, but shifted once left, with an extra zero appended, and then each nonzero digit incremented by one:
20, 320, 20220, 324020, 4604320, 64004220, 824203020, , ...

Crossrefs

Row 2 of A275960.
First differences of A265907.

Formula

a(n) = A255411(A265907(n))
a(n) = A265907(n+1) - A265907(n).
Showing 1-4 of 4 results.