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.

A247084 a(n)=0 when n<=0: Starting with n=1, a(n) = 1 + the sum of the digital sums of a(0) through a(n-4).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 3, 4, 5, 7, 10, 14, 19, 26, 27, 32, 42, 50, 59, 64, 70, 75, 89, 99, 106, 118, 135, 153, 160, 170, 179, 188, 195, 203, 220, 237, 252, 257, 261, 273, 282, 296, 305, 317, 329, 346, 354, 365, 379, 392, 404, 418, 437, 451, 459, 472, 486, 496, 514
Offset: 0

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Author

Bob Selcoe, Nov 17 2014

Keywords

Examples

			a(15) = 32 because (0+1+1+1+1+2+3+4+5+7+1+0+1+4) + 1 = 32.
		

Crossrefs

Cf. A007953, A219675, A244510 (related).

Programs

  • Mathematica
    a247084[n_Integer] := Module[{t = Table[1, {i, n + 1}], j, k},
    t[[1]] = 0; j = 6; While[j <= Length[t], t[[j]] = Sum[Plus @@ IntegerDigits[t[[k]]], {k, 1, j - 4}]; ++]; Drop[t, {2}]]; a247084[59] (* Michael De Vlieger, Nov 29 2014 *)
  • PARI
    lista(nn) = {v = vector(nn); for (n=2, nn, v[n] = 1 + sum(i=1, n-4, if (n-4 > 0, sumdigits(v[i])));); v;} \\ Michel Marcus, Nov 18 2014

Formula

a(n) = 1 + Sum_{k=0..n-4} digsum(a(k)).
a(n) = a(n-1) + digsum(a(n-4)).

Extensions

More terms from Michel Marcus, Nov 18 2014