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A125841 Numbers n such that previous_prime(n)=n-sd and next_prime(n)=n+sd where sd is sum of the distinct prime factors of n. 1
144, 288, 1728, 5184, 7168, 11760, 21632, 21952, 73500, 110592, 113400, 114244, 151263, 153790, 186624, 205800, 235298, 250563, 663552, 708588, 1404928, 2976750, 3449628, 4738500, 5265000, 7077888, 9437184, 11529602, 11745162 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

14267656658790241528591830756844692582808594415616 is a 50-digit term of this sequence. 493009335 is the smallest number n such that previous_prime(n)=n-s and next_prime(n)=n+s where s is sum of the prime factors of n. What is the next number with the same property?

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

113400=2^3*3^4*5^2*7 is in the sequence because previous_prime(113400)

=113400-(2+3+5+7) and next_prime(113400)=113400+(2+3+5+7).

MATHEMATICA

Do[If[c=Apply[Plus, PrimeFactorList[n]]; n-c==PreviousPrime[n]&&n+c== NextPrime[n], Print[n]], {n, 4, 20000000}]

CROSSREFS

Cf. A125840.

Sequence in context: A250773 A262245 A134341 * A320457 A154051 A217584

Adjacent sequences:  A125838 A125839 A125840 * A125842 A125843 A125844

KEYWORD

easy,nonn,base

AUTHOR

Farideh Firoozbakht, Feb 04 2007, corrected Feb 08 2007

STATUS

approved

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Last modified June 19 06:47 EDT 2019. Contains 324218 sequences. (Running on oeis4.)