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

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A248412 Smallest prime p such that p - 2^e is also prime power (A053810) in exactly n cases for nonnegative integers e. 0
 149, 2, 5, 11, 83, 829, 3331, 32941, 176417, 854929, 2233531, 12699571, 47924959, 763597201 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS first case when A115230 equals n. 0: 149, 331, 373, 509, 701, 757, 809, 877, 907, 997, 1019, ...; 1: 2, 3, 127, 163, 179, 191, 193, 223, 239, 251, 269, 311, ...; 2: 5, 7, 23, 37, 47, 53, 59, 67, 71, 79, 97, 101, 103, ...; 3: 11, 13, 17, 19, 29, 31, 41, 43, 61, 73, 89, 131, 137, ...; 4: 83, 113, 139, 181, 199, 293, 353, 571, 593, 601, 619, ...; 5: 829, 1217, 1487, 2131, 2341, 2551, 2971, 4051, 4261, ...; 6: 3331, 12109, 14551, 17393, 18233, 22279, 22307, 22741, ...; 7: 32941, 34369, 44029, 49433, 53633, 67189, 95717, 99833, ...; 8: 176417, 304771, 314723, 314779, 349667, 414707, 451937, ...; 9: 854929, 1297651, 1328927, 1784723, 2164433, 2488909, ...; 10: 2233531, 6026089, 7475389, 7623229, 9644911, 10019551, ...; 11: 12699571, 18464123, 52849879, 78127339, 79303579, 84397463, ...; 12: 47924959, 153309649, 204797059, 248685923, 273865219, ...; 13: 763597201, ...; ... LINKS FORMULA a(n) <= A244917(n) for n>0. MATHEMATICA f[p_] := Length@ Table[q = p - 2^exp; If[ PrimeNu@ q == 1, {q}, Sequence @@ {}], {exp, 0, Floor@ Log2@ p}]; t = Table[0, {20}]; p = 2; While[p < 1000000000, a = f[p] +1; If[a < 101 && t[[a]] == 0, t[[a]] == p; Print[{a -1, p}]]; p = NextPrime@ p]; t CROSSREFS Cf. A115230, A244917, zeroth row A095842, first row A095841. Sequence in context: A223829 A223973 A263554 * A182874 A268428 A190654 Adjacent sequences:  A248409 A248410 A248411 * A248413 A248414 A248415 KEYWORD nonn AUTHOR Robert G. Wilson v, Oct 06 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.

Last modified December 6 15:23 EST 2021. Contains 349563 sequences. (Running on oeis4.)