login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A219957 Numbers expressible as 2*p + 3*q exactly in two ways, where p and q are primes (not necessarily distinct). 4
19, 25, 31, 35, 37, 49, 53, 59, 65, 85, 89 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

89 = 2*37 + 3*5 = 2*19 + 3*17.

MATHEMATICA

mx = 1000; s = Table[0, {mx}]; Do[a = 2 Prime[i] + 3 Prime[k]; s[[a]]++, {k, PrimePi[(mx - 4)/3]}, {i, PrimePi[(mx - 3 Prime[k])/2]}]; Flatten@Position[s, 2]

CROSSREFS

Cf. A079026, A219955, A219956.

Sequence in context: A175356 A134255 A061841 * A276437 A129071 A066125

Adjacent sequences:  A219954 A219955 A219956 * A219958 A219959 A219960

KEYWORD

nonn,fini,full

AUTHOR

Zak Seidov, Dec 02 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)