A218448 First of a run of 5 consecutive numbers with same prime signature.

204323, 3252571, 5205074, 7201674, 20182921, 28387953, 36193650, 43216722, 51049537, 56155074, 57070850, 61961315, 62167075, 65425473, 76647074, 82507473, 92658049, 95943321, 100498849, 107236449, 109751473, 110899321, 112198075, 112477849, 116736323

Offset

1,1

Comments

A number n is in this sequence iff n and n+1 is in A175590; also: iff n and n+2 are in A052214 (in which case n+1 is in A052214, too); and also: iff {n,n+1,n+2,n+3} are in A052213.

A034173(6) = A218448(62) = A218448(63)-1 is the least term n such that n+1 is also in the sequence.

Links

M. F. Hasler and Donovan Johnson, Table of n, a(n) for n = 1..1000 (first 140 terms from M. F. Hasler)

Prog

(PARI) is_A218448(n)={my(f); !for(i=0, 4, f!=(f=vecsort(factor(n+i)[, 2])) & i & return)}
(PARI) f(k)=vecsort(factor(k)[, 2]~, , 4)
t=f(n=2); while(n<1e8, for(i=n+1, n+4, tt=f(i); if(tt!=t, n=i; t=tt; next(2))); print1(n", "); n++) \\ Charles R Greathouse IV, Oct 28 2012

Crossrefs

Cf. A034173, A034174, A006558, A083790, A052213, A052214, A175590.

Sequence in context: A235854 A203911 A237014 * A234836 A206093 A333015

Adjacent sequences: A218445 A218446 A218447 * A218449 A218450 A218451

Keyword

nonn

Author

M. F. Hasler, Oct 28 2012

Extensions

a(6)-a(8) from Charles R Greathouse IV, Oct 28 2012

a(9)-a(25) from Donovan Johnson, Oct 28 2012

Values up to a(140) computed using b175590.txt from Charles R Greathouse IV - M. F. Hasler, Oct 28 2012

Status

approved