A225418 Composite numbers which contain their sum of the distinct prime factors (sopf function) as a substring.

25, 32, 54, 98, 125, 126, 128, 140, 196, 230, 243, 246, 255, 256, 315, 322, 348, 366, 392, 512, 520, 576, 625, 810, 828, 896, 1024, 1029, 1060, 1080, 1152, 1166, 1216, 1224, 1225, 1243, 1330, 1395, 1400, 1458, 1462, 1512, 1536, 1548, 1575, 1647, 1708, 1792, 1824, 1872, 1875

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

17061 is in the sequence because 17061=3*11*11*47, sopf(17061)=3+11+47=61, substring of 17061.

Mathematica

Select[Range[2000], CompositeQ[#]&&SequenceCount[IntegerDigits[#], IntegerDigits[ Total[ FactorInteger[#][[All, 1]]]]]>0&] (* Harvey P. Dale, Apr 29 2018 *)

Prog

(PARI) sopf(n)= {s=0; f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) }
Indigit(a, b)={ u=Vec(Str(a)); v=Vec(Str(b)); indi=0; la=#u; lb=#v; i=1; while(i<=la-lb+1&&indi==0, d=0; for(x=1, lb, if(v[x]==u[i+x-1], d+=1)); indi=(d==lb) ; i+=1); return(indi)}
{ for(i=1, 10^4, if(Indigit(i, sopf(i))&&isprime(i)==0, print(i)))}

Crossrefs

Sequence in context: A107258 A258876 A263029 * A035140 A050694 A107608

Adjacent sequences: A225415 A225416 A225417 * A225419 A225420 A225421

Keyword

nonn,base

Author

Antonio Roldán, May 07 2013

Status

approved