A305675 Run lengths of successive equal terms in A305671.

1, 6, 7, 20, 20, 33, 20, 54, 33, 30, 31, 107, 7, 16, 33, 8, 10, 71, 274, 216, 618, 17, 224, 44, 1154, 36, 1715, 10, 1035, 54, 237, 37, 96, 22, 190, 187, 487, 60, 57, 15, 298, 124, 5326, 59, 22, 8, 49, 59, 1666, 23, 52, 33, 439, 69, 6247, 646, 9643, 163, 7259

Offset: 1

Author

Felix Fröhlich, Jun 08 2018

Keywords

• nonn

Comments

First differences of A305672 UNION A305673.

Crossrefs

Cf. A305671, A305672, A305673, A305674, A305676.

Programs

Mathematica

Block[{c = Select[Range[10^4], CompositeQ], s}, s = DivisorSigma[1, c]; Most[Length /@ SplitBy[#, # == 0 &]] &@ Array[If[Length@ # == 1, #[[1, 1]], 0] &@ Last@ SplitBy[SortBy[Tally@ Take[s, #], Last], Last] &, Length@ s]] (* Michael De Vlieger, Jul 22 2018 *)

PARI

composite(n) = my(i=0); forcomposite(c=1, , i++; if(i==n, return(c)))
mcv(v) = my(w=vecsort(v, , 8), count=vector(#w), ind=0, i=0); for(x=1, #w, for(y=1, #v, if(w[x]==v[y], count[x]++))); for(k=1, #count, if(count[k]==vecmax(count), ind=k; i++)); if(i > 1, return(0), return(w[ind]))
a305671(n) = my(v=[]); for(k=1, n, v=concat(v, sigma(composite(k)))); mcv(v)
terms(n) = my(i=0, j=1); for(k=1, oo, if(a305671(k)==a305671(k+1), j++, if(j > 0, print1(j, ", "); i++; j=1)); if(i==n, break))
terms(20) \\ Print initial 20 terms of the sequence