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A064351 Numbers n such that n and n+1 have the same sum and number of prime divisors (with repetition). 1
6867, 57075, 113283, 155708, 230124, 244035, 250995, 351075, 437715, 508563, 667628, 742508, 1065843, 1095315, 1166067, 1302092, 1379907, 1431212, 1496780, 2373452, 2519343, 2978787, 2992220, 3164524, 3583772, 4799011, 4826835, 5103875, 5140316, 5535404 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harry J. Smith and Donovan Johnson, Table of n, a(n) for n = 1..1000 (first 80 terms from Harry J. Smith)

MATHEMATICA

snpd[n_]:=Module[{fi=FactorInteger[n]}, {Total[Flatten[Table[#[[1]], {#[[2]]}]&/@fi]], Total[Transpose[fi][[2]]]}]; Flatten[Position[Partition[ Array[ snpd, 5600000], 2, 1], _?(#[[1]]==#[[2]]&), {1}, Heads->False]] (* Harvey P. Dale, Nov 29 2013 *)

PROG

(PARI) sopfr(n)= { local(c, f, s=0); G=0; f=factor(n); for(i=1, matsize(f)[1], c=f[i, 2]; G+=c; s+=f[i, 1]*c); return(s) } { n=c=s=0; for (m=1, 10^9, us=sopfr(m + 1); if(c==G && s==us, write("b064351.txt", n++, " ", m); if (n==100, break)); c=G; s=us ) } \\ Harry J. Smith, Sep 12 2009

CROSSREFS

Cf. A001414, A001222.

Sequence in context: A013811 A013892 A154086 * A062678 A018848 A031581

Adjacent sequences:  A064348 A064349 A064350 * A064352 A064353 A064354

KEYWORD

nonn

AUTHOR

Jason Earls, Oct 15 2001

EXTENSIONS

a(25) - a(27) from Harry J. Smith, Sep 12 2009

STATUS

approved

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Last modified October 16 21:10 EDT 2019. Contains 328103 sequences. (Running on oeis4.)