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A161165 The n-th twin prime plus the n-th isolated prime. 7
5, 28, 44, 58, 66, 84, 98, 112, 120, 138, 156, 186, 192, 228, 236, 268, 276, 318, 332, 370, 390, 406, 414, 456, 474, 498, 510, 528, 536, 580, 588, 606, 614, 648, 654, 670, 680, 712, 722, 786, 792, 868, 878, 898, 912, 948, 954, 1020, 1026, 1078, 1112, 1146, 1158, 1180 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..54.

FORMULA

a(n) = A001097(n) + A007510(n).

EXAMPLE

a(1) = 3 +  2 =  5;

a(2) = 5 + 23 = 28;

a(3) = 7 + 37 = 44.

MAPLE

isA001097 := proc(n) isprime(n) and (isprime(n+2) or isprime(n-2)) ; end proc:

A001097 := proc(n) if n = 1 then 3; else for p from procname(n-1)+2 by 2 do if isA001097(p) then return p end if; end do: end if; end proc:

isA007510 := proc(n) isprime(n) and not isprime(n+2) and not isprime(n-2) ; end proc:

A007510 := proc(n) if n = 1 then 2; else for p from procname(n-1)+1 do if isA007510(p) then return p end if; end do: end if; end proc:

A161165 := proc(n) A001097(n) + A007510(n) ; end proc:

seq(A161165(n), n=1..100) ; # R. J. Mathar, Mar 18 2010

# alternate program

isA001097 := proc(n) if isprime(n) then isprime(n+2) or isprime(n-2) ; else false; end if; end proc:

isA007510 := proc(n) if isprime(n) then not isprime(n+2) and not isprime(n-2) ; else false; end if; end proc:

A001097 := proc(n) option remember; if n = 1 then 3; else for a from procname(n-1)+1 do if isA001097(a) then return a; end if; end do: end if; end proc:

A007510 := proc(n) option remember; if n = 1 then 2; else for a from procname(n-1)+1 do if isA007510(a) then return a; end if; end do: end if; end proc:

A161165 := proc(n) A001097(n)+A007510(n) ; end proc: seq(A161165(n), n=1..90) ; # R. J. Mathar, Mar 29 2010

CROSSREFS

Cf. A001097, A007510.

Sequence in context: A321236 A218346 A106679 * A063140 A316560 A275709

Adjacent sequences:  A161162 A161163 A161164 * A161166 A161167 A161168

KEYWORD

nonn,easy

AUTHOR

Juri-Stepan Gerasimov, Jun 04 2009

EXTENSIONS

Entries checked by R. J. Mathar, Mar 18 2010

STATUS

approved

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Last modified June 5 14:36 EDT 2020. Contains 334841 sequences. (Running on oeis4.)