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A186413 a(n) is the number of odd primes p < prime(n)^2 such that prime(n)# + p is prime with prime(n)# primorial of prime(n). 2
1, 2, 5, 8, 16, 18, 20, 28, 25, 30, 40, 46, 41, 53, 56, 73, 62, 66, 81, 93, 85, 84, 89, 97, 101, 127, 121, 122, 119, 128, 150, 141, 144, 152, 150, 143, 174, 203, 197, 195, 196, 194, 213, 213, 218, 223, 230, 235, 249, 258, 256, 244, 264, 262 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is not so far from prime(n).

LINKS

Pierre CAMI, Table of n, a(n) for n = 1..176

EXAMPLE

prime(1)#=2 2+3=5 5>2^2 so a(1)=1

prime(2)#=6 6+5=11,6+7=13 11>3*3 so a(2)=2

PROG

SCRIPT

DIM nn, 1

DIM kk

DIM cc

DIM dd

DIMS tt

DIMS ss

OPENFILEOUT myout, res

LABEL loopn

SET nn, nn+1

SET kk, nn

SET cc, 0

SET dd, 0

LABEL loopk

SET kk, kk+1

IF p(kk)>p(nn)^2 THEN GOTO a

SETS tt, %d, %d, %d\,; nn; p(nn); -p(kk)

PRP p(nn)#-p(kk), tt

IF ISPRIME THEN SET cc, cc+1

IF ISPRP THEN SET cc, cc+1

SETS tt, %d, %d, %d\,; nn; p(nn); p(kk)

PRP p(nn)#+p(kk), tt

IF ISPRIME THEN SET dd, dd+1

IF ISPRP THEN SET dd, dd+1

GOTO loopk

LABEL a

SETS ss, %d, %d, %d\,; nn; cc; dd

WRITE myout, ss

GOTO loopn

CROSSREFS

Cf. A185398.

Sequence in context: A285291 A065618 A257548 * A080084 A065093 A168470

Adjacent sequences:  A186410 A186411 A186412 * A186414 A186415 A186416

KEYWORD

nonn

AUTHOR

Pierre CAMI, Feb 21 2011

STATUS

approved

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Last modified July 23 16:50 EDT 2017. Contains 289690 sequences.