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 A032758 Undulating primes (digits alternate). 38
 2, 3, 5, 7, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 131, 151, 181, 191, 313, 353, 373, 383, 727, 757, 787, 797, 919, 929, 18181, 32323, 35353, 72727, 74747, 78787, 94949, 95959, 1212121, 1616161, 323232323, 383838383 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sometimes called "smoothly undulating primes", to distinguish them from A059168. REFERENCES C. A. Pickover, "Keys to Infinity", Wiley 1995, p. 159,160. C. A. Pickover, "Wonders of Numbers", Oxford New York 2001, Chapter 52, pp. 123-124, 316-317. LINKS Michael S. Branicky, Table of n, a(n) for n = 1..131 (terms 1..100 from Sean A. Irvine) C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Zentralblatt review Charles W. Trigg, Nine-digit patterned palindromic primes, Crux Mathematicorum, Vol. 7, No. 6, June - July 1981, pp. 168-170. MATHEMATICA a[n_] := DeleteDuplicates[Take[IntegerDigits[n], {1, -1, 2}]]; b[n_] := DeleteDuplicates[Take[IntegerDigits[n], {2, -1, 2}]]; t={}; Do[p=Prime[n]; If[p<10, AppendTo[t, p], If[Length[a[p]] == Length[b[p]] == 1 && a[p][[1]] != b[p][[1]], AppendTo[t, p]]], {n, 3*10^7}]; t (* Jayanta Basu, May 04 2013 *) PROG (Python) from itertools import count, islice from sympy import isprime, primerange def agen(): # generator of terms yield from (p for p in primerange(2, 100) if p != 11) yield from (t for t in (int((A+B)*d2+A) for d2 in count(1) for A in "1379" for B in "0123456789" if A != B) if isprime(t)) print(list(islice(agen(), 51))) # Michael S. Branicky, Jun 09 2022 CROSSREFS Cf. A033619, A030291, A059168, A242541, A004022. Sequence in context: A308078 A050757 A059168 * A106118 A029743 A344620 Adjacent sequences: A032755 A032756 A032757 * A032759 A032760 A032761 KEYWORD nonn,base,easy AUTHOR Patrick De Geest, May 15 1998 EXTENSIONS Sequence corrected by Juri-Stepan Gerasimov, Jan 28 2010 Offset corrected by Arkadiusz Wesolowski, Sep 13 2011 STATUS approved

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Last modified November 27 03:04 EST 2022. Contains 358362 sequences. (Running on oeis4.)