login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A249339 Positions of ones in A249336; positions of zeros in A249338. 5
1, 2, 4, 6, 14, 21, 40, 51, 71, 81, 98, 132, 143, 194, 241, 258, 297, 323, 380, 398, 436, 479, 491, 543, 570, 630, 737, 759, 765, 829, 836, 873, 1068, 1101, 1210, 1215, 1370, 1415, 1469, 1515, 1550, 1607, 1682, 1701, 1854, 1872, 1904, 1932, 2117, 2245, 2294, 2304, 2344 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

For n >= 2, a(n) = 1 + A249340(n-1).

PROG

(PARI)

allocatemem(234567890);

A049084(n) = if(isprime(n), primepi(n), 0); \\ This function from Charles R Greathouse IV

A056239(n) = { my(f); if(1==n, 0, f=factor(n); sum(i=1, #f~, f[i, 2] * A049084(f[i, 1]))); }

A249339_write_bfile(up_to_n) = { my(counts, n, k, a_k); counts = vector(min((2^24)-8, up_to_n^2)); n = 0; k = 0; a_k = 1; while(n < up_to_n, k++; if((0 == A056239(a_k)), n++; write("b249339.txt", n, " ", k)); counts[1+A056239(a_k)]++; a_k = counts[1+A056239(a_k)]); };

A249339_write_bfile(10000);

(Scheme, with Antti Karttunen's IntSeq-library, two alternative definitions)

(define A249339 (MATCHING-POS 1 1 (lambda (n) (= 1 (A249336 n)))))

(define A249339 (ZERO-POS 1 1 A249338))

CROSSREFS

Cf. A249336, A249338, A249340, A249341.

Sequence in context: A226302 A337499 A284886 * A332754 A307676 A084685

Adjacent sequences:  A249336 A249337 A249338 * A249340 A249341 A249342

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 26 2014

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 March 7 19:13 EST 2021. Contains 341928 sequences. (Running on oeis4.)