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A305675 Run lengths of successive equal terms in A305671. 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

First differences of A305672 UNION A305673.

LINKS

Table of n, a(n) for n=1..59.

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 *)

PROG

(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

CROSSREFS

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

Sequence in context: A285840 A285819 A287760 * A210605 A175262 A081348

Adjacent sequences:  A305672 A305673 A305674 * A305676 A305677 A305678

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Jun 08 2018

STATUS

approved

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Last modified August 18 15:00 EDT 2019. Contains 326106 sequences. (Running on oeis4.)