cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A130971 Smallest prime p, such that either |A000040(n)-p| or A000040(n)+p is of the form 2^k.

Original entry on oeis.org

2, 2, 3, 3, 3, 3, 13, 3, 7, 3, 23, 5, 23, 11, 17, 11, 5, 3, 3, 7, 41, 47, 19, 73, 31, 37, 71, 43, 19, 97, 131, 3, 73, 11, 107, 23, 29, 131, 89, 83, 163, 53, 127, 191, 59, 71, 83, 191, 29, 101, 23, 17, 113, 5, 193, 7, 13, 239, 149, 277, 229, 37, 179, 307, 199, 61, 181, 353, 283
Offset: 1

Views

Author

Antti Karttunen, Jun 19 2007

Keywords

Links

Crossrefs

Cf. A130971, A130972, A103150.

Programs

  • Scheme
    (define (A130971 n) (let ((p1 (A000040 n))) (let loop ((i 1) (p2 2)) (cond ((pow2? (abs (- p1 p2))) p2) ((pow2? (+ p1 p2)) p2) (else (loop (+ i 1) (A000040 (+ i 1))))))))
(define (pow2? n) (and (> n 0) (zero? (A004198bi n (- n 1)))))

Extensions

Extended by Ray Chandler, Aug 06 2010

A130972 Positions of records in A130971.

Original entry on oeis.org

1, 3, 7, 11, 21, 22, 24, 30, 31, 41, 44, 55, 58, 60, 64, 68, 77, 86, 88, 94, 109, 118, 120, 126, 134, 140, 146, 151, 155, 168, 176, 181, 187, 197, 201, 204, 205, 213, 217, 221, 228, 230, 239, 251, 256, 260, 274, 286, 290, 295, 298, 450, 549, 1379, 2456, 5658
Offset: 1

Views

Author

Antti Karttunen, Jun 19 2007

Keywords

Links

Crossrefs

Cf. A103149, A103150.

Extensions

Extended by Ray Chandler, Aug 06 2010

A103149 a(1)=3, a(n) = A000040(A130972(n)).

Original entry on oeis.org

3, 5, 17, 31, 73, 79, 89, 113, 127, 179, 193, 257, 271, 281, 311, 337, 389, 443, 457, 491, 599, 647, 659, 701, 757, 809, 839, 877, 907, 997, 1049, 1087, 1117, 1201, 1229, 1249, 1259, 1303, 1327, 1381, 1439, 1451, 1499, 1597, 1619, 1657, 1759, 1871, 1889, 1933
Offset: 1

Views

Author

Lei Zhou, Feb 05 2005

Keywords

Crossrefs

A102632, A103150.

Programs

  • Mathematica
    pmin = 0; pm0 = 2^16384; mpm = 0; ppm = 0; mcm = 0; pcm = 0; p = 1; While[pmin < pm0, pmin = pm0; = 0; nu2 = 1; cm = nu2 - p; cp = nu2 + p; While[(n < 16383) && (cm < pmin), If[(cp < pmin) && PrimeQ[cp], pmin = cp];acm = Abs[cm]; If[(mpm < pmin) && PrimeQ[p], mpm = pmin; ppm = p; Save["pinc.txt", {mpm, ppm}]]; p = p + 2]
  • Scheme
    (define (A103149 n) (if (= n 1) 3 (A000040 (A130972 n))))

Extensions

Edited, Scheme-code added and starting offset changed from 0 to 1 by Antti Karttunen, Jun 19 2007
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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